Virtual Journal of Nanoscale Science & Technology

No Evidence of Magnitude Clustering in an Aftershock Sequence of Nano- and Picoseismicity

Jorn Davidsen, Grzegorz Kwiatek, and Georg Dresen
One of the hallmarks of our current understanding of seismicity as highlighted by the epidemic-type-aftershock sequence model is that the magnitudes of earthquakes are independent of one another and can be considered as randomly drawn from the Gutenberg-Richter distribution. This assumption forms th ... [Phys. Rev. Lett. 108, 038501 ] published .

Chiral Quasicrystalline Order and Dodecahedral Geometry in Exceptional Families of Viruses

O. V. Konevtsova, S. B. Rochal, and V. L. Lorman
On the example of exceptional families of viruses we (i) show the existence of a completely new type of matter organization in nanoparticles, in which the regions with a chiral pentagonal quasicrystalline order of protein positions are arranged in a structure commensurate with the spherical topology ... [Phys. Rev. Lett. 108, 038102 ] published .

Competition between curls and plectonemes near the buckling transition of stretched supercoiled DNA

John F. Marko and Sebastien Neukirch
Recent single-molecule experiments have observed that formation of a plectonemically supercoiled region in a stretched, twisted DNA proceeds via abrupt formation of a small plectonemic bubble. A detailed mesoscopic model is presented for the formation of plectonemic domains, including their position ... [Phys. Rev. E 85, 011908 ] published .

Carrier dynamics in InN nanorod arrays

Hyeyoung Ahn, Chih-Cheng Yu, Pyng Yu, Jau Tang, Yu-Liang Hong et al.
In this report, we investigated ultrafast carrier dynamics of vertically aligned indium nitride (InN) nanorod (NR) arrays grown by molecular-beam epitaxy on Si(111) substrates. Dominant band filling effects were observed and were attributed to a partial bleaching of absorption at the probe wavelengt ... [Opt. Express 20, 769 (2012)] published Tue Jan 24, 2012.

Enhancement of light extraction in GaN-based light-emitting diodes using rough beveled ZnO nanocone arrays

Zhengmao Yin, Xiaoyan Liu, Yongzhong Wu, Xiaopeng Hao, and Xiangang Xu
A remarkable enhancement of light extraction efficiency in GaN-based blue light-emitting diodes (LEDs) with rough beveled ZnO nanocone arrays grown on the planar indium tin oxide (ITO) layer is reported. The light output power of LEDs with rough beveled ZnO nanocone arrays was increased by about 110 ... [Opt. Express 20, 1013 (2012)] published Tue Jan 24, 2012.

Morphological instability leading to formation of porous anodic oxide films

Kurt R. Hebert, Sergiu P. Albu, Indhumati Paramasivam, and Patrik Schmuki
Electrochemical oxidation of metals, in solutions where the oxide is somewhat soluble, produces anodic oxides with highly regular arrangements of pores. Although porous aluminium and titanium oxides have found extensive use in functional nanostructures, pore initiation and self-ordering are not yet ... [Nature Mater. 11, 162 (2012)] published Thu Jan 26, 2012.

High electrochemical activity of the oxide phase in model ceriaPt and ceriaNi composite anodes

William C. Chueh, Yong Hao, WooChul Jung, and Sossina M. Haile
Fuel cells, and in particular solid-oxide fuel cells (SOFCs), enable high-efficiency conversion of chemical fuels into useful electrical energy and, as such, are expected to play a major role in a sustainable-energy future. A key step in the fuel-cell energy-conversion process is the electro-oxidati ... [Nature Mater. 11, 155 (2012)] published Thu Jan 26, 2012.

Single Shot Spatial and Temporal Coherence Properties of the SLAC Linac Coherent Light Source in the Hard X-Ray Regime

C. Gutt, P. Wochner, B. Fischer, H. Conrad, M. Castro-Colin et al.
We measured the transverse and longitudinal coherence properties of the Linac Coherent Light Source (LCLS) at SLAC in the hard x-ray regime at 9 keV photon energy on a single shot basis. Speckle patterns recorded in the forward direction from colloidal nanoparticles yielded the transverse coherence ... [Phys. Rev. Lett. 108, 024801 ] published .

Crossover between Weak Antilocalization and Weak Localization in a Magnetically Doped Topological Insulator

Minhao Liu, Jinsong Zhang, Cui-Zu Chang, Zuocheng Zhang, Xiao Feng et al.
We report transport studies on magnetically doped BiSe topological insulator ultrathin films grown by molecular beam epitaxy. The magnetotransport behavior exhibits a systematic crossover between weak antilocalization and weak localization with the change of magnetic impurity concentration, temperat ... [Phys. Rev. Lett. 108, 036805 ] published .

Physical ageing of the contact line on colloidal particles at liquid interfaces

David M. Kaz, Ryan McGorty, Madhav Mani, Michael P. Brenner, and Vinothan N. Manoharan
Youngs law predicts that a colloidal sphere in equilibrium with a liquid interface will straddle the two fluids, its height above the interface defined by an equilibrium contact angle. This has been used to explain why colloids often bind to liquid interfaces, and has been exploited in emulsificati ... [Nature Mater. 11, 138 (2012)] published Thu Jan 26, 2012.

Heterogeneous Crystal Nucleation: The Effect of Lattice Mismatch

Gyula I. Toth, Gyorgy Tegze, Tamas Pusztai, and Laszlo Granasy
A simple dynamical density functional theory is used to investigate freezing of an undercooled liquid in the presence of a crystalline substrate. We find that the adsorption of the crystalline phase on the substrate, the contact angle, and the height of the nucleation barrier are nonmonotonic functi ... [Phys. Rev. Lett. 108, 025502 ] published .

Perovskite phase transformation in 0.65Pb(MgNb)O-0.35PbTiO nanoparticles derived by sol-gel

Satyendra Singh and S. B. Krupanidhi
Fabrication of 0.65Pb(MgNb)O-0.35PbTiO (PMN-PT) nanoparticles with an average size of about 40 nm and their phase transformation behavior from pyrochlore to perovskite phase is investigated. A novel sol-gel method was used for the synthesis of air-stable and precipitate-free diol-based sol of PMN-PT ... [J. Appl. Phys. 111, 024314 (2012)] published Thu Jan 26, 2012.

Plasmonic light trapping leads to responsivity increase in colloidal quantum dot photodetectors

F. Pelayo Garcia de Arquer, Fiona J. Beck, Maria Bernechea, and Gerasimos Konstantatos
We report broadband responsivity enhancement in PbS colloidal quantum dot (CQDs) photoconductive photodetectors due to absorption increase offered by a plasmonic scattering layer of Ag metal nanoparticles. Responsivity enhancements are observed in the near infrared with a maximum 2.4-fold increase n ... [Appl. Phys. Lett. 100, 043101 (2012)] published Mon Jan 23, 2012.

Morphological control of hybrid polymer-quantum dot solar cells with electron acceptor ligands

Mathieu Boivin, Sebastien Lamarre, Jonathan Tessier, Marie-Eve Lecavalier, Ahmed Najari et al.
We integrate the electro-attractive conjugated molecule tetrafluoro-tetracyano-quinodimethane (FTCNQ) in the active layer of polymer-CdSe colloidal quantum dot (cQD) solar cells. The addition of this molecule enhances cQD dispersion inside the polymer. In tuning its concentration, we can optimize th ... [Appl. Phys. Lett. 100, 033302 (2012)] published Fri Jan 20, 2012.

Aspect-ratio-dependent phase transitions and concentration fluctuations in aqueous colloidal dispersions of charged platelike particles

Daisuke Yamaguchi, Nobuyoshi Miyamoto, Takako Fujita, Teruyuki Nakato, Satoshi Koizumi et al.
Phase transitions of aqueous colloidal dispersions of charged platelike particles of niobate nanosheets were investigated as a function of the aspect ratio (r) and particle volume concentration ([cursive phi]) by means of small-angle neutron scattering and small-angle x-ray scattering. The results e ... [Phys. Rev. E 85, 011403 ] published .

Effective Viscosity of Confined Hydrocarbons

I. M. Sivebaek, V. N. Samoilov, and B. N. J. Persson
We present molecular dynamics friction calculations for confined hydrocarbon films with molecular lengths from 20 to 1400 carbon atoms. We find that the logarithm of the effective viscosity eta for nanometer-thin films depends linearly on the logarithm of the shear rate: logeta=C-nlog gamma-dot, whe ... [Phys. Rev. Lett. 108, 036102 ] published .

Self-Sustained Localized Structures in a Boundary-Layer Flow

Yohann Duguet, Philipp Schlatter, Dan S. Henningson, and Bruno Eckhardt
When a boundary layer starts to develop spatially over a flat plate, only disturbances of sufficiently large amplitude survive and trigger turbulence subcritically. Direct numerical simulation of the Blasius boundary-layer flow is carried out to track the dynamics in the region of phase space separa ... [Phys. Rev. Lett. 108, 044501 ] published .

Reorientation dynamics of nanoconfined water: Power-law decay, hydrogen-bond jumps, and test of a two-state model

Damien Laage and Ward H. Thompson
The reorientation dynamics of water confined within nanoscale, hydrophilic silica pores are investigated using molecular dynamics simulations. The effect of surface hydrogen-bonding and electrostatic interactions are examined by comparing with both a silica pore with no charges (representing hydroph ... [J. Chem. Phys. 136, 044513 (2012)] published Wed Jan 25, 2012.

Noncollinear Fe spin structure in (Sm-Co)/Fe exchange-spring bilayers: Layer-resolved Fe Mossbauer spectroscopy and electronic structure calculations

V. M. Uzdin, A. Vega, A. Khrenov, W. Keune, V. E. Kuncser et al.
Magnetization reversal in nanoscale (Sm-Co)/Fe (hard/soft) bilayer exchange-spring magnets with in-plane uniaxial magnetic anisotropy was investigated by magnetometry, conversion-electron Mossbauer spectroscopy (CEMS) and atomistic Fe spin-structure calculations. Magnetization loops along the easy d ... [Phys. Rev. B 85, 024409 ] published .

Mechanism for recombination of radiation-induced point defects at interphase boundaries

X.-Y. Liu, B. P. Uberuaga, M. J. Demkowicz, T. C. Germann, A. Misra et al.
Interfaces play a critical role in the extraordinary resistance to irradiation damage in nanostructured materials. Atomistic simulations are performed to examine defect production and recovery at incoherent interphase boundaries with different atomic structures. The interstitials produced during cas ... [Phys. Rev. B 85, 012103 ] published .

Surface modification by subsurface pressure induced diffusion

Claus G. Zimmermann
Polycrystalline Ag, covered with a nm thin siloxane layer, was irradiated with ultraviolet light in vacuum at 500 K. Ag particles of different aspect ratios, 501000 nm in size, formed on the surface, including a small fraction of nanorods. Pressurized water vapor bubbles are created in the subsurfac ... [Appl. Phys. Lett. 100, 041908 (2012)] published Thu Jan 26, 2012.

Spark discharge formation in an inhomogeneous electric field under conditions of runaway electron generation

Tao Shao (邵涛), Victor F. Tarasenko, Cheng Zhang (章程), Mikhail I. Lomaev, Dmitrii A. Sorokin et al.
In this article we report on work where the formation of a spark in nanosecond high-voltage discharges was studied in nitrogen, nitrogen-methane mixtures, and air at increased pressures under the conditions of runaway electron generation. Voltage pulses of amplitude ~90 and ~250 kV were applied to a ... [J. Appl. Phys. 111, 023304 (2012)] published Mon Jan 23, 2012.

Mid-infrared spectroscopy of molecular ions in helium nanodroplets

Xiaohang Zhang, Nils B. Brauer, Giel Berden, Anouk M. Rijs, and Marcel Drabbels
High resolution IR spectra of aniline, styrene, and 1,1-diphenylethylene cations embedded in superfluid helium nanodroplets have been recorded in the 3001700 cm range using a free-electron laser as radiation source. Comparison of the spectra with available gas phase data reveals that the helium envi ... [J. Chem. Phys. 136, 044305 (2012)] published Tue Jan 24, 2012.

Vibrational energy relaxation of benzene dimer and trimer in the CH stretching region studied by picosecond time-resolved IR-UV pump-probe spectroscopy

Ryoji Kusaka, Yoshiya Inokuchi, and Takayuki Ebata
Vibrational energy relaxation (VER) of the Fermi polyads in the CH stretching vibration of the benzene dimer (Bz) and trimer (Bz) has been investigated by picosecond (ps) time-resolved IR-UV pump-probe spectroscopy in a supersonic beam. The vibrational bands in the 30003100 cm region were excited by ... [J. Chem. Phys. 136, 044304 (2012)] published Mon Jan 23, 2012.

Ultrafast Viscous Permeation of Organic Solvents Through Diamond-Like Carbon Nanosheets

Santanu Karan, Sadaki Samitsu, Xinsheng Peng, Keiji Kurashima, and Izumi Ichinose
Chemical, petrochemical, energy, and environment-related industries strongly require high-performance nanofiltration membranes applicable to organic solvents. To achieve high solvent permeability, filtration membranes must be as thin as possible, while retaining mechanical strength and solvent resis ... [Science 335, 444 (2012)] published Tue Jan 24, 2012.

A new experimental setup designed for the investigation of irradiation of nanosystems in the gas phase: A high intensity mass-and-energy selected cluster beam

G. Bruny, S. Eden, S. Feil, R. Fillol, K. El Farkh et al.
DIAM (Dispositif d'Irradiation d'Agregats Moleculaires) is a new experimental setup devoted to investigate processes induced by irradiation at the nanoscale. The DIAM apparatus is based on a combination of techniques including a particle beam from high-energy physics, a cluster source from molecular ... [Rev. Sci. Instrum. 83, 013305 (2012)] published Fri Jan 20, 2012.

Charge transport across metal/molecular (alkyl) monolayer-Si junctions is dominated by the LUMO level

We compare the charge transport characteristics of heavy-doped p- and n-Si-alkyl chain/Hg junctions. Based on negative differential resistance in an analogous semiconductor-inorganic insulator/metal junction we suggest that for both p- and n-type junctions, the energy difference between the Fermi le ... [Phys. Rev. B 85, 045433 ] published .

Ambipolar transition voltage spectroscopy: Analytical results and experimental agreement

Ioan Baldea
This work emphasizes that the transition voltages V for both bias polarities (V [greater, less] 0) should be used to properly determine the energy offset [eh] of the molecular orbital closest to electrodes' Fermi level and the bias asymmetry gamma in molecular junctions. Accurate analytical formulas ... [Phys. Rev. B 85, 035442 ] published .

Characterization of 1064nm nanosecond laser-induced damage on antireflection coatings grown by atomic layer deposition

Zhichao Liu, Songlin Chen, Ping Ma, Yaowei Wei, Yi Zheng et al.
Damage tests are carried out at 1064nm to measure the laser resistance of TiO/AlOand HfO/AlO antireflection coatings grown by atomic layer deposition (ALD). The damage results are determined by S-on-1 and R-on-1 tests. Interestingly, the damage performance of ALD coatings is similar to those grown b ... [Opt. Express 20, 854 (2012)] published Tue Jan 24, 2012.

Correlated nucleation and self-accommodating kinetic pathway of ferroelectric phase transformation

Jie E. Zhou, Tian-Le Cheng, and Yu U. Wang
Mechanisms of nucleation and growth of domains during ferroelectric phase transformation are investigated by using theoretical and computational approaches. It is shown that ferroelectric phase transformation exhibits some peculiar behaviors due to strong long-range dipole-dipole-like interactions i ... [J. Appl. Phys. 111, 024105 (2012)] published Wed Jan 25, 2012.

Random and Ordered Phases of Off-Lattice Rhombus Tiles

Stephen Whitelam, Isaac Tamblyn, Peter H. Beton, and Juan P. Garrahan
We study the covering of the plane by nonoverlapping rhombus tiles, a problem well studied only in the limiting case of dimer coverings of regular lattices. We go beyond this limit by allowing tiles to take any position and orientation on the plane, to be of irregular shape, and to possess different ... [Phys. Rev. Lett. 108, 035702 ] published .

Atomistic pseudopotential theory of spin relaxation in self-assembled InGaAs/GaAs quantum dots at zero magnetic field

Hai Wei, Ming Gong, Guang-Can Guo, and Lixin He
An atomistic pseudopotential calculation of the spin-flip time (T) of electrons and holes mediated by acoustic phonons in self-assembled InGaAs/GaAs quantum dots at zero magnetic field is presented. At low magnetic field, the first-order process is suppressed, and the second-order process becomes do ... [Phys. Rev. B 85, 045317 ] published .

Bragg wave coupling in self-assembled opal photonic crystals

Rajesh V. Nair and B. N. Jagatap
The optical properties of three-dimensionally-ordered self-assembled photonic crystals are studied in the Bragg wave coupling regime. Angle-resolved photonic stop gap measurements show the Bragg wave coupling extending over an angular range of 18 degrees . The new diffraction peak originating at the ... [Phys. Rev. A 85, 013829 ] published .

Reconfigurable self-assembly through chiral control of interfacial tension

Thomas Gibaud, Edward Barry, Mark J. Zakhary, Mir Henglin, Andrew Ward et al.
From determining the optical properties of simple molecular crystals to establishing the preferred handedness in highly complex vertebrates, molecular chirality profoundly influences the structural, mechanical and optical properties of both synthetic and biological matter on macroscopic length scal ... [Nature 481, 348 (2012)] published Fri Jan 20, 2012.

Self-assembly of uniform polyhedral silver nanocrystals into densest packings and exoticsuperlattices

Joel Henzie, Michael Grnwald, Asaph Widmer-Cooper, Phillip L. Geissler, and Peidong Yang
Understanding how polyhedra pack into extended arrangements is integral to the design and discovery of crystalline materials at all length scales. Much progress has been made in enumerating and characterizing the packing of polyhedral shapes, and the self-assembly of polyhedral nanocrystals into or ... [Nature Mater. 11, 131 (2012)] published Thu Jan 26, 2012.

Nuclear Spins of Ionized Phosphorus Donors in Silicon

Lukas Dreher, Felix Hoehne, Martin Stutzmann, and Martin S. Brandt
We demonstrate the coherent control and electrical readout of ionized phosphorus donor nuclear spins in Si. By combining time-programed optical excitation with coherent electron spin manipulation, we selectively ionize the donors depending on their nuclear spin state, exploiting a spin-dependent rec ... [Phys. Rev. Lett. 108, 027602 ] published .

Configuration interaction calculations of the controlled phase gate in double quantum dot qubits

Erik Nielsen, Richard P. Muller, and Malcolm S. Carroll
We consider qubit coupling resulting from the capacitive coupling between two double quantum dot (DQD) singlet-triplet qubits. Calculations of the coupling when the two DQDs are detuned symmetrically or asymmetrically are performed using a full configuration interaction (CI). The full CI reveals beh ... [Phys. Rev. B 85, 035319 ] published .

Relaxation and readout visibility of a singlet-triplet qubit in an Overhauser field gradient

C. Barthel, J. Medford, H. Bluhm, A. Yacoby, C. M. Marcus et al.
Using single-shot charge detection in a GaAs double quantum dot, we investigate spin relaxation time (T) and readout visibility of a two-electron singlet-triplet qubit following single-electron dynamic nuclear polarization (DNP). For magnetic fields up to 2 T, the DNP cycle is in all cases found to ... [Phys. Rev. B 85, 035306 ] published .

Majorana zero modes in a quantum Ising chain with longer-ranged interactions

Yuezhen Niu, Suk Bum Chung, Chen-Hsuan Hsu, Ipsita Mandal, S. Raghu et al.
A one-dimensional Ising model in a transverse field can be mapped onto a system of spinless fermions with p-wave superconductivity. In the weak-coupling BCS regime, it exhibits a zero-energy Majorana mode at each end of the chain. Here, we consider a variation of the model, which represents a superc ... [Phys. Rev. B 85, 035110 ] published .

Generation of maximally-polarization-entangled photons on a chip

Sergei V. Zhukovsky, Lukas G. Helt, Dongpeng Kang, Payam Abolghasem, Amr S. Helmy et al.
We propose a method of generating maximally-polarization-entangled states by type-II spontaneous parametric down-conversion in Bragg reflection waveguides. Analytic expressions for the group velocities of down-converted modes are used to engineer zero group-velocity mismatch at the operating point, ... [Phys. Rev. A 85, 013838 ] published .

Multiple-spin coherence transfer in linear Ising spin chains and beyond: Numerically optimized pulses and experiments

Manoj Nimbalkar, Robert Zeier, Jorge L. Neves, S. Begam Elavarasi, Haidong Yuan et al.
We study multiple-spin coherence transfers in linear Ising spin chains with nearest-neighbor couplings. These constitute a model for efficient information transfers in future quantum computing devices and for many multidimensional experiments for the assignment of complex spectra in nuclear magnetic ... [Phys. Rev. A 85, 012325 ] published .

Entanglement in stationary nonequilibrium states at high energies

Marko ZnidariC
In recent years it has been found that quantum systems can posses entanglement in equilibrium thermal states provided temperature is low enough. In the present work we explore a possibility of having entanglement in nonequilibrium stationary states. We show analytically that, in a simple one-dimensi ... [Phys. Rev. A 85, 012324 ] published .

Spin chains for robust state transfer: Modified boundary couplings versus completely engineered chains

Analia Zwick, Gonzalo A. Alvarez, Joachim Stolze, and Omar Osenda
Quantum state transfer in the presence of static disorder and noise is one of the main challenges in building quantum computers. We compare the quantum state transfer properties for two classes of qubit chains under the influence of static disorder. In fully engineered chains all nearest-neighbor co ... [Phys. Rev. A 85, 012318 ] published .

Decoherence control: Universal protection of two-qubit states and two-qubit gates using continuous driving fields

Adam Zaman Chaudhry and Jiangbin Gong
A field configuration utilizing local static fields and a few continuous-wave driving fields is constructed to achieve universal (but low-order) protection of two-qubit states. That is, two-qubit states can be protected against arbitrary system-environment coupling with control fields if their frequ ... [Phys. Rev. A 85, 012315 ] published .

Maximally entangled gapped ground state of lattice fermions

David L. Feder
Entanglement between the constituents of a quantum system is an essential resource in the implementation of many quantum processes and algorithms. Indeed, universal quantum computation is possible by measuring individual qubits that constitute highly entangled cluster states. In this work, it is sho ... [Phys. Rev. A 85, 012312 ] published .

Topologically protected measurement-based quantum computation on the thermal state of a nearest-neighbor two-body Hamiltonian with spin-3/2 particles

Keisuke Fujii and Tomoyuki Morimae
Recently, Li et al. [Phys. Rev. Lett. 107, 060501 (2011)] have demonstrated that topologically protected measurement-based quantum computation can be implemented on the thermal state of a nearest-neighbor two-body Hamiltonian with spin-2 and spin-3/2 particles provided that the temperature is smalle ... [Phys. Rev. A 85, 010304 ] published .

Dipole Coupling of a Double Quantum Dot to a Microwave Resonator

T. Frey, P. J. Leek, M. Beck, A. Blais, T. Ihn et al.
We demonstrate the realization of a hybrid solid-state quantum device, in which a semiconductor double quantum dot is dipole coupled to the microwave field of a superconducting coplanar waveguide resonator. The double dot charge stability diagram extracted from measurements of the amplitude and phas ... [Phys. Rev. Lett. 108, 046807 ] published .

Magnetic-Field Probing of an SU(4) Kondo Resonance in a Single-Atom Transistor

G. C. Tettamanzi, J. Verduijn, G. P. Lansbergen, M. Blaauboer, M. J. Calderon et al.
Semiconductor devices have been scaled to the point that transport can be dominated by only a single dopant atom. As a result, in a Si fin-type field effect transistor Kondo physics can govern transport when one electron is bound to the single dopant. Orbital (valley) degrees of freedom, apart from ... [Phys. Rev. Lett. 108, 046803 ] published .

Two-Photon Quantum Interference from Separate Nitrogen Vacancy Centers in Diamond

Hannes Bernien, Lilian Childress, Lucio Robledo, Matthew Markham, Daniel Twitchen et al.
We report on the observation of quantum interference of the emission from two separate nitrogen vacancy (NV) centers in diamond. Taking advantage of optically induced spin polarization in combination with polarization filtering, we isolate a single transition within the zero-phonon line of the nonre ... [Phys. Rev. Lett. 108, 043604 ] published .

Benchmarking a Quantum Teleportation Protocol in Superconducting Circuits Using Tomography and an Entanglement Witness

M. Baur, A. Fedorov, L. Steffen, S. Filipp, M. P. da Silva et al.
Teleportation of a quantum state may be used for distributing entanglement between distant qubits in quantum communication and for quantum computation. Here we demonstrate the implementation of a teleportation protocol, up to the single-shot measurement step, with superconducting qubits coupled to a ... [Phys. Rev. Lett. 108, 040502 ] published .

Majorana Modes in Time-Reversal Invariant s-Wave Topological Superconductors

Shusa Deng, Lorenza Viola, and Gerardo Ortiz
We present a time-reversal invariant s-wave superconductor supporting Majorana edge modes. The multiband character of the model together with spin-orbit coupling are key to realizing such a topological superconductor. We characterize the topological phase diagram by using a partial Chern number sum, ... [Phys. Rev. Lett. 108, 036803 ] published .

Entanglement of Three-Qubit Greenberger-Horne-ZeilingerSymmetric States

Christopher Eltschka and Jens Siewert
The first characterization of mixed-state entanglement was achieved for two-qubit states in Werner's seminal work [Phys. Rev. A 40, 4277 (1989)]. A physically important extension concerns mixtures of a pure entangled state [such as the Greenberger-Horne-Zeilinger (GHZ) state] and the unpolarized sta ... [Phys. Rev. Lett. 108, 020502 ] published .

Measuring which-path information with coupled electronic Mach-Zehnder interferometers

J. Dressel, Y. Choi, and A. N. Jordan
We theoretically investigate a generalized which-path measurement on an electronic Mach-Zehnder Interferometer (MZI) implemented via Coulomb coupling to a second electronic MZI acting as a detector. The use of contextual values, or generalized eigenvalues, enables the precise construction of which-p ... [Phys. Rev. B 85, 045320 ] published .

Edge-mode combinations in the entanglement spectra of non-Abelian fractional quantum Hall states on the torus

Zhao Liu, Emil J. Bergholtz, Heng Fan, and Andreas M. Lauchli
We present a detailed analysis of bipartite entanglement in the non-Abelian Moore-Read fractional quantum Hall state of bosons and fermions on the torus. In particular, we show that the entanglement spectra can be decomposed into intricate combinations of different sectors of the conformal field the ... [Phys. Rev. B 85, 045119 ] published .

Quantum state transfer between hybrid qubits in a circuit QED

Zhi-Bo Feng
In this Brief Report, we propose a theoretical scheme to transfer quantum states between superconducting charge qubits and semiconductor spin qubits in a circuit QED device. Under dispersive conditions, resonator-assisted state transfer between qubits can be performed controllably only by addressing ... [Phys. Rev. A 85, 014302 ] published .

Fracturing graphene by chlorination: A theoretical viewpoint

M. Ijas, P. Havu, and A. Harju
Motivated by a recent photochlorination experiment [B. Li et al., ACS Nano 5, 5957 (2011)], we study theoretically the interaction of chlorine with graphene. In previous theoretical studies, covalent binding between chlorine and carbon atoms has been elusive upon adsorption to the graphene basal pla ... [Phys. Rev. B 85, 035440 ] published .

Dirac donor states controlled by magnetic field in gapless and gapped graphene

Jia-Lin Zhu, Songyang Sun, and Ning Yang
In this paper, the exact solutions of Dirac electronic states of graphene in Coulomb and magnetic fields are acquired. The Coulomb field not only causes the splitting of Landau levels in gapless graphene but also leads to the variation of the energy level ordering in gapped graphene. The dependence ... [Phys. Rev. B 85, 035429 ] published .

Observation of Landau-level-like quantization at 77 K along a strained-induced graphene ridge

Hui Yan, Yi Sun, Lin He, Jia-Cai Nie, and Moses H. W. Chan
Recent studies show that the electronic structures of graphene can be modified by strain, and it was predicted that strain in graphene can induce peaks in the local density of states (LDOS), mimicking Landau levels (LLs) generated in the presence of a large magnetic field. Here we report the scannin ... [Phys. Rev. B 85, 035422 ] published .

Influence of charge transfer doping on the morphologies of C islands on hydrogenated diamond C(100)-(2 x 1)

Markus Nimmrich, Markus Kittelmann, Philipp Rahe, Wolfgang Harneit, Andrew J. Mayne et al.
The adsorption and island formation of C fullerenes on the hydrogenated C(100)-(2 x 1):H diamond surface is studied using high-resolution noncontact atomic force microscopy in ultrahigh vacuum. At room temperature, C fullerene molecules assemble into monolayer islands, exhibiting a hexagonally close ... [Phys. Rev. B 85, 035420 ] published .

Superfluidity of dipole excitons in the presence of band gaps in two-layer graphene

Oleg L. Berman, Roman Ya. Kezerashvili, and Klaus Ziegler
We propose to observe superfluidity of quasi-two-dimensional dipole excitons in double-layer graphene in the presence of band gaps. The energy spectrum of the collective excitations, the sound spectrum, and the effective exciton mass are functions of the energy gaps, density, and interlayer separati ... [Phys. Rev. B 85, 035418 ] published .

Trions in semiconducting single-walled carbon nanotubes

Kouta Watanabe and Kenichi Asano
We study trions (charged excitons), a complex of an electron-hole pair and an additional electron or hole, in semiconducting single-walled carbon nanotubes (s-SWCNT), by means of the exact diagonalization of the realistic Hamiltonian based on the kp scheme and on the screened Hartree-Fock approximat ... [Phys. Rev. B 85, 035416 ] published .

Nonlinear strain effects in double-resonance Raman bands of graphite, graphene, and related materials

Elena del Corro, Mercedes Taravillo, and Valentin G. Baonza
We analyze the influence of biaxial strain on the double-resonance (D and 2D) Raman bands of graphite-related materials. A substantial nonlinear dependence of these bands with the strain is observed, evidencing a quite different effect on the electronic structure around the K and Gamma points of the ... [Phys. Rev. B 85, 033407 ] published .

Layer-resolved conductivities in multilayer graphene

Takeo Wakutsu, Masaaki Nakamura, and Balazs Dora
We study interlayer transport of multilayer graphenes in a magnetic field with various stacking structures (AB, ABC, and AA types) by calculating the Hall and longitudinal conductivities as functions of the Fermi energy. Their behavior depends strongly on the stacking structures and selection of the ... [Phys. Rev. B 85, 033403 ] published .

Graphene production by laser shot on graphene oxide: An ab initio prediction

Hong Zhang and Yoshiyuki Miyamoto
By performing the first-principles simulation of electron-ion dynamics based on the time-dependent density-functional theory, we propose a way to produce graphene from graphene oxides by means of the laser-induced reduction without using chemical species. Epoxy and hydroxyl groups on graphene sheets ... [Phys. Rev. B 85, 033402 ] published .

Interband effects of magnetic field on Hall conductivity in the multilayered massless Dirac fermion system alpha-(BEDT-TTF)I

Naoya Tajima, Reizo Kato, Shigeharu Sugawara, Yutaka Nishio, and Koji Kajita
We have discovered a two-dimensional zero-gap material with a layered structure in the organic conductor alpha-(BEDT-TTF)I under high hydrostatic pressure. In contrast to graphene, the electron-hole symmetry is not good except at the vicinity of the Dirac points. Thus, the temperature dependence of ... [Phys. Rev. B 85, 033401 ] published .

Atomic-scale transport in epitaxial graphene

Shuai-Hua Ji, J. B. Hannon, R. M. Tromp, V. Perebeinos, J. Tersoff et al.
The high carrier mobility of graphene is key to its applications,and understanding the factors that limit mobility is essential for future devices. Yet, despite significant progress, mobilities in excess of the 210cmVs demonstrated in free-standing graphene films have not been duplicated in convent ... [Nature Mater. 11, 114 (2012)] published Thu Jan 26, 2012.

Structural and electronic properties of single-wall carbon nanotubes with various nitrogen content

V. G. Boutko, A. A. Gusev, T. N. Shevtsova, and Yu. G. Pashkevich
The band structure of a carbon-nitrogen nanotube of zigzag type (8, 0) with nitrogen atom concentrations of 6.25%, 12.5%, and 25% and armchair (5, 5) carbon-nitrogen nanotube with nitrogen atom concentrations of 10% and 20% is calculated within the density functional theory approach. The calculation ... [Low Temp. Phys. 37, 1021 (2012)] published Wed Jan 25, 2012.

Electrical properties of C and Si codoped GaAs layers

Jiro Nishinaga and Yoshiji Horikoshi
C uniformly doped GaAs and C, Si codoped GaAs layers are grown by a migration enhanced epitaxy method. C doped GaAs layers show a single and sharp diffraction peak in x-ray diffraction and only an LO phonon peak is confirmed, indicating that the crystalline quality is fairly good. All of the C doped ... [J. Vac. Sci. Technol. B 30, 02B116 (2012)] published Tue Jan 24, 2012.

Evidence of ferroelectricity and phase transition in pressed diphenylalanine peptide nanotubes

Igor Bdikin, Vladimir Bystrov, Svitlana Kopyl, Rui P. G. Lopes, Ivonne Delgadillo et al.
Self-assembled peptide nanotubes (PNT) are unique nanoscale objects having a great potential for a multitude of applications. Strong piezoactivity and polar properties in aromatic dipeptides were recently observed in stand-alone nanotubes using piezoresponse force microscopy and 2 harmonic generatio ... [Appl. Phys. Lett. 100, 043702 (2012)] published Tue Jan 24, 2012.

Ceasing of voltage switching amongst graphitic shells in multiwalled carbon nanotubes: A route toward stability

Neha Kulshrestha, Abhishek Misra, Reeti Bajpai, Soumyendu Roy, and D. S. Misra
Weakly interacting graphitic shells of different resistivities within multiwalled carbon nanotubes (MWNTs) cause instability in current and thus limit their reliability for electronic device applications. We here demonstrate voltage switching amongst graphitic shells of MWNTs by applying current swe ... [Appl. Phys. Lett. 100, 043505 (2012)] published Tue Jan 24, 2012.

High magnetic field annealing effect on visible photoluminescence enhancement of TiO nanotube arrays

Mingjie Yang, Wei Liu, Jia-Lin Sun, and Jia-Lin Zhu
TiO nanotube arrays with remarkable visible photoluminescence were prepared by high magnetic field annealing in air at 450 degrees C due to the involvement of oxygen vacancies (OVs). A field with the intensities of 0, 2, 4, 6, and 8 T were applied in the annealing processing, along the directions s ... [Appl. Phys. Lett. 100, 043106 (2012)] published Wed Jan 25, 2012.

Improved electron field emission from morphologically disordered monolayer graphene

Srikrishna Pandey, Padmnabh Rai, Shashikant Patole, Fethullah Gunes, Gi-Duk Kwon et al.
Graphene was synthesized on copper foil by thermal chemical vapor deposition technique. To investigate the field electron emission property, planar graphene (PG) and morphologically disordered graphene (MDG) were fabricated on the doped silicon substrate by transfer of as-grown graphene. Incorporati ... [Appl. Phys. Lett. 100, 043104 (2012)] published Tue Jan 24, 2012.

Transforming graphite to nanoscale diamonds by a femtosecond laser pulse

R. Nuske, A. Jurgilaitis, H. Enquist, M. Harb, Y. Fang et al.
Formation of cubic diamond from graphite following irradiation by a single, intense, ultra-short laser pulse has been observed. Highly oriented pyrolytic graphite (HOPG) samples were irradiated by a 100 fs pulse with a center wavelength of 800 nm. Following laser exposure, the HOPG samples were stud ... [Appl. Phys. Lett. 100, 043102 (2012)] published Mon Jan 23, 2012.

Recoverable electrical transition in a single graphene sheet for application in nonvolatile memories

Chaoxing Wu, Fushan Li, Yongai Zhang, and Tailiang Guo
The electrical properties of a resistive-switching memory based on a single graphene sheet suspended on a patterned indium-tin-oxide electrode pair were investigated. Current-voltage measurements on the planar device showed a large ON/OFF ratio (~10) and excellent retention ability in ambient condit ... [Appl. Phys. Lett. 100, 042105 (2012)] published Wed Jan 25, 2012.

Size of the Localized Electron Emission Sites on a Closed Multiwalled Carbon Nanotube

Erwin C. Heeres, Tjerk H. Oosterkamp, and Niels de Jonge
We have measured the size of the localized electron emission sites on multiwalled carbon nanotubes (MWNTs) with caps closed by a fullerenelike structure. MWNTs were individually mounted on tungsten support tips and imaged with a field emission microscope (FEM). The magnification of the FEM was calib ... [Phys. Rev. Lett. 108, 036804 ] published .

Synthesis of monolithic graphenegraphite integrated electronics

Jang-Ung Park, SungWoo Nam, Mi-Sun Lee, and Charles M. Lieber
Encoding electronic functionality into nanoscale elements during chemical synthesis has been extensively explored over the past decade as the key to developing integrated nanosystems with functions defined by synthesis. Graphene has been recently explored as a two-dimensional nanoscale material, an ... [Nature Mater. 11, 120 (2012)] published Thu Jan 26, 2012.

Measurement of Quantum Noise in a Carbon Nanotube Quantum Dot in the Kondo Regime

J. Basset, A. Yu. Kasumov, C. P. Moca, G. Zarand, P. Simon et al.
The current emission noise of a carbon nanotube quantum dot in the Kondo regime is measured at frequencies nu of the order or higher than the frequency associated with the Kondo effect kT/h, with T the Kondo temperature. The carbon nanotube is coupled via an on-chip resonant circuit to a quantum noi ... [Phys. Rev. Lett. 108, 046802 ] published .

Effect of van der Waals interaction on energetics and transport properties of a single anthracene molecule adsorbed or confined inside a carbon nanotube

L. Debbichi, Y. J. Dappe, and M. Alouani
The energetics and transport properties of a single aromatic molecule (CH) in interaction with a metallic single-walled carbon nanotube (SWCNT) have been studied using state-of-the-art density functional calculations. In both adsorption and encapsulation configurations, we show that the fundamental ... [Phys. Rev. B 85, 045437 ] published .

Native defects in hybrid C/BN nanostructures by density functional theory calculations

J. M. Pruneda
First-principles calculations of substitutional defects and vacancies are performed for zigzag-edged hybrid C/BN nanosheets and nanotubes which recently have been proposed to exhibit half-metallic properties. The formation energies show that defects form preferentially at the interfaces between grap ... [Phys. Rev. B 85, 045422 ] published .

Theory of thermal transport in multilayer hexagonal boron nitride and nanotubes

L. Lindsay and D. A. Broido
We present a theory for the lattice thermal conductivity kappa of single-walled boron nitride nanotubes (BNNTs) and multilayer hexagonal boron nitride (MLBN), which is based on an exact numerical solution of the phonon Boltzmann equation. Coupling between layers in MLBN and nanotube curvature in BNN ... [Phys. Rev. B 85, 035436 ] published .

Raman spectroscopy of substrate-induced compression and substrate doping in thermally cycled graphene

Chun-Chung Chen, Wenzhong Bao, Chia-Chi Chang, Zeng Zhao, Chun Ning Lau et al.
By thermally cycling single layer graphene in air, we observe irreversible upshifts of the Raman G and 2D bands of 24 and 23 cm, respectively. These upshifts are attributed to an in-plane compression of the graphene induced by the mismatch of thermal expansion coefficients between the graphene and t ... [Phys. Rev. B 85, 035431 ] published .

Side-dependent electron escape from graphene- and graphane-like SiC layers

Paola Gori, Olivia Pulci, Margherita Marsili, and Friedhelm Bechstedt
The structural and electronic properties of SiC-based two-dimensional (2D) crystals are studied by means of density functional theory and many-body perturbation theory. Such properties cannot simply be interpolated between graphene and silicene. The replacement of half of the C atoms by Si atoms ope ... [Appl. Phys. Lett. 100, 043110 (2012)] published Thu Jan 26, 2012.

Anomalous electron transport in back-gated field-effect transistors with TiTe semimetal thin-film channels

J. Khan, C. M. Nolen, D. Teweldebrhan, D. Wickramaratne, R. K. Lake et al.
The authors report on graphene-like mechanical exfoliation of thin films of titanium ditelluride and investigation of their electronic properties. The exfoliated crystalline TiTe films were used as the channel layers in the back-gated field-effect transistors fabricated with Ti/Al/Au metal contacts ... [Appl. Phys. Lett. 100, 043109 (2012)] published Thu Jan 26, 2012.

Effective energy gap of the double-walled carbon nanotubes with field effect transistors ambipolar characteristics

Takahiro Morimoto, Akihiro Kuno, Shota Yajima, Koji Ishibashi, Koji Tsuchiya et al.
We have investigated the transport property of the double-walled carbon nanotubes (DWCNT)-field effect transistor (FET) devices with HfO insulating layers at room temperature and 4.2 K. These devices show the ambipolar FET characteristics after deposition of HfO insulating layer. The off-regions of ... [Appl. Phys. Lett. 100, 043107 (2012)] published Thu Jan 26, 2012.

Enhancing interwall load transfer by vacancy defects in carbon nanotubes

David Santo Pietro, Chun Tang, and Changfeng Chen
Structural defects usually reduce the load carrying capacity of materials. Here, we show by molecular dynamics simulations an anomalous vacancy-defect-induced enhancement of interwall load transfer in annealed carbon nanotubes (CNTs). The large increase of load transfer mainly stems from the hybrid ... [Appl. Phys. Lett. 100, 033118 (2012)] published Fri Jan 20, 2012.

Wave-Function Mapping of Graphene Quantum Dots with Soft Confinement

D. Subramaniam, F. Libisch, Y. Li, C. Pauly, V. Geringer et al.
Using low-temperature scanning tunneling spectroscopy, we map the local density of states of graphene quantum dots supported on Ir(111). Because of a band gap in the projected Ir band structure around the graphene K point, the electronic properties of the QDs are dominantly graphenelike. Indeed, we ... [Phys. Rev. Lett. 108, 046801 ] published .

Measuring the Complex Admittance of a Carbon Nanotube Double Quantum Dot

S. J. Chorley, J. Wabnig, Z. V. Penfold-Fitch, K. D. Petersson, J. Frake et al.
We investigate radio-frequency (rf) reflectometry in a tunable carbon nanotube double quantum dot coupled to a resonant circuit. By measuring the in-phase and quadrature components of the reflected rf signal, we are able to determine the complex admittance of the double quantum dot as a function of ... [Phys. Rev. Lett. 108, 036802 ] published .

Ultrafast luminescence kinetics of metallic single-walled carbon nanotubes: Possible evidence for excitonic luminescence

Takeshi Koyama, Satoru Shimizu, Takeshi Saito, Yasumitsu Miyata, Hisanori Shinohara et al.
In metallic systems, strong screening of the Coulomb interaction between an electron and a hole by free electrons largely prevents the formation of an exciton. In one-dimensional metallic systems, however, the screening effect is significantly reduced. Recent theoretical and experimental studies sug ... [Phys. Rev. B 85, 045428 ] published .

Role of structure of C-terminated 4H-SiC(000[overline 1]) surface in growth of graphene layers: Transmission electron microscopy and density functional theory studies

J. Borysiuk, J. Soltys, R. Bozek, J. Piechota, S. Krukowski et al.
The principal structural defects in graphene layers, synthesized on a carbon-terminated face, i.e., the SiC(000[overline 1]) face of a 4H-SiC substrate, are investigated using microscopic methods. Results of high-resolution transmission electron microscopy (HRTEM) reveal their atomic arrangement. Th ... [Phys. Rev. B 85, 045426 ] published .

Exact renormalization group computation of the optical conductivity of graphene

Alessandro Giuliani and Vieri Mastropietro
The optical conductivity of a system of electrons on the honeycomb lattice interacting through a retarded electromagnetic field is computed by exact renormalization-group (RG) methods. By truncating the exact RG expression at one loop we find that the conductivity has the universal value pi/2 times ... [Phys. Rev. B 85, 045420 ] published .

Probing substrate effects in the carbon-projected band structure of graphene on Pt(111) through resonant inelastic x-ray scattering

Srivats Rajasekaran, Sarp Kaya, Toyli Anniyev, Hirohito Ogasawara, and Anders Nilsson
The unoccupied and occupied sigma and pi bands of graphene on Pt(111) were measured using near-edge x-ray absorption spectroscopy (XAS) and resonant inelastic x-ray scattering (RIXS) at the carbon K edge. Elemental specificity and crystal-momentum conservation allows for detection of the dispersive ... [Phys. Rev. B 85, 045419 ] published .

Si intercalation/deintercalation of graphene on 6H-SiC(0001)

C. Xia, S. Watcharinyanon, A. A. Zakharov, R. Yakimova, L. Hultman et al.
The intercalation and deintercalation mechanisms of Si deposited on monolayer graphene grown on SiC(0001) substrates and after subsequent annealing steps are investigated using low-energy electron microscopy (LEEM), photoelectron spectroscopy (PES), and micro-low-energy electron diffraction ([mu]-LE ... [Phys. Rev. B 85, 045418 ] published .

Sources of negative tunneling magnetoresistance in multilevel quantum dots with ferromagnetic contacts

Sonja Koller, Milena Grifoni, and Jens Paaske
We analyze distinct sources of spin-dependent energy level shifts and their impact on the tunneling magnetoresistance (TMR) of interacting quantum dots coupled to collinearly polarized ferromagnetic leads. Level shifts due to virtual charge fluctuations can be quantitatively evaluated within a diagr ... [Phys. Rev. B 85, 045313 ] published .

Effects of static charging and exfoliation of layered crystals

M. Topsakal and S. Ciraci
Using a first-principle plane-wave method we investigate the effects of static charging on the structural, electronic, and magnetic properties of suspended, single-layer graphene, graphane, fluorographene, BN, and MoS in a honeycomb structure. The limitations of periodic boundary conditions in the t ... [Phys. Rev. B 85, 045121 ] published .

Skyrme crystal in bilayer and multilayer graphene

Yasuhisa Sakurai and Daijiro Yoshioka
The ground state of the two-dimensional electron systems in Bernal bilayer and ABC-stacked multilayer graphenes in the presence of a strong magnetic field is investigated with the Hartree-Fock approximation. Phase diagrams of the systems are obtained, focusing on charge density wave states including ... [Phys. Rev. B 85, 045108 ] published .

Interface structure of graphene on SiC(000[overline 1])

N. Srivastava, Guowei He, Luxmi, and R. M. Feenstra
Graphene films prepared by heating the SiC(000[overline 1]) surface (the C-face of the {0001} surfaces) in a vacuum or in a Si-rich environment are compared. It is found that different interface structures occur for the two situations. The former yields a well known 3 x 3 reconstructed interface, ... [Phys. Rev. B 85, 041404 ] published .

Ultrafast carrier dynamics and terahertz emission in optically pumped graphene at room temperature

S. Boubanga-Tombet, S. Chan, T. Watanabe, A. Satou, V. Ryzhii et al.
We report, within a picosecond time scale, fast relaxation and relatively slow recombination dynamics of photogenerated electrons and holes in an exfoliated graphene under infrared pulse excitation. We conduct time-domain spectroscopic studies using an optical pump and terahertz probe with an optica ... [Phys. Rev. B 85, 035443 ] published .

Fluctuations, Dynamics, and the Stretch-Coil Transition of Single Actin Filaments in Extensional Flows

Vasily Kantsler and Raymond E. Goldstein
Semiflexible polymers subject to hydrodynamic forcing play an important role in cytoskeletal motions in the cell, particularly when filaments guide molecular motors whose motions create flows. Near hyperbolic stagnation points, filaments experience a competition between bending elasticity and tensio ... [Phys. Rev. Lett. 108, 038103 ] published .

Synthesis of single-component metallic glasses by thermal spray of nanodroplets on amorphous substrates

Qi An, Sheng-Nian Luo, William A. Goddard, III, W. Z. Han, B. Arman et al.
We show that single component metallic glasses can be synthesized by thermal spray coating of nanodroplets onto an amorphous substrate. We demonstrate this using molecular dynamics simulations of nanodroplets up to 30 nm that the spreading of the nanodroplets during impact on a substrate leads to su ... [Appl. Phys. Lett. 100, 041909 (2012)] published Thu Jan 26, 2012.

Numerical demonstration of the reciprocity among elemental relaxation and driven-flow problems for a rarefied gas in a channel

Shigeru Takata and Masashi Oishi
Relaxations from a uniform mass/heat flow and flows driven by an external force/temperature-gradient for a rarefied gas between two parallel plates are studied on the basis of the kinetic theory of gases. By numerical computations of the linearized BhatnagarGrossKrook model of the Boltzmann equation ... [Phys. Fluids 24, 012003 ] published .

Anisotropic Pair Correlations and Structure Factors of Confined Hard-Sphere Fluids: An Experimental and Theoretical Study

K. Nygard, R. Kjellander, S. Sarman, S. Chodankar, E. Perret et al.
We address the fundamental question: how are pair correlations and structure factors of hard-sphere fluids affected by confinement between hard planar walls at close distance? For this purpose, we combine x-ray scattering from colloid-filled nanofluidic channel arrays and first-principles inhomogene ... [Phys. Rev. Lett. 108, 037802 ] published .

Hamiltonian Traffic Dynamics in Microfluidic-Loop Networks

Raphael Jeanneret, Julien-Piera Vest, and Denis Bartolo
Recent microfluidic experiments revealed that large particles advected in a fluidic loop display long-range hydrodynamic interactions. However, the consequences of such couplings on the traffic dynamics in more complex networks remain poorly understood. In this Letter, we focus on the transport of a ... [Phys. Rev. Lett. 108, 034501 ] published .

Entropic Splitter for Particle Separation

D. Reguera, A. Luque, P. S. Burada, G. Schmid, J. M. Rubi et al.
We present a particle separation mechanism which induces the motion of particles of different sizes in opposite directions. The mechanism is based on the combined action of a driving force and an entropic rectification of the Brownian fluctuations caused by the asymmetric form of the channel along w ... [Phys. Rev. Lett. 108, 020604 ] published .

Droplet formation in microfluidic T-junction generators operating in the transitional regime. II. Modeling

Tomasz Glawdel, Caglar Elbuken, and Carolyn L. Ren
This is the second part of a two-part study on the generation of droplets at a microfluidic T-junction operating in the transition regime. In the preceding paper [Phys. Rev. E 85, 016322 (2012)], we presented our experimental observations of droplet formation and decomposed the process into three se ... [Phys. Rev. E 85, 016323 ] published .

Fluid flow due to collective non-reciprocal motion of symmetrically-beating artificial cilia

S. N. Khaderi, J. M. J. den Toonder, and P. R. Onck
Using a magneto-mechanical solid-fluid numerical model for permanently magnetic artificial cilia, we show that the metachronal motion of symmetrically beating cilia establishes a net pressure gradient in the direction of the metachronal wave, which creates a unidirectional flow. The flow generated i ... [Biomicrofluidics 6, 014106 (2012)] published Fri Jan 20, 2012.

A mathematical model of mixing enhancement in microfluidic channel with a constriction under periodic electro-osmotic flow

Zhongbin Xu, Yue Yang, Damien Vadillo, Xiaodong Ruan, and Xin Fu
A microfluidic channel with a constriction produced poor mixing conditions under periodic electro-osmotic flow. However, the mixing performance may be enhanced significantly by altering other parameters. Numerical simulations are used to investigate the effect of the direct current electric field (E ... [Appl. Phys. Lett. 100, 041907 (2012)] published Thu Jan 26, 2012.

Droplet formation in microfluidic T-junction generators operating in the transitional regime. I. Experimental observations

Tomasz Glawdel, Caglar Elbuken, and Carolyn L. Ren
This is the first part of a two-part study on the generation of droplets at a microfluidic T-junction operating in the transition regime where confinement of the droplet creates a large squeezing pressure that influences droplet formation. In this regime, the operation of the T-junction depends on t ... [Phys. Rev. E 85, 016322 ] published .

Electromagnetic propulsion and separation by chirality of nanoparticles in liquids

E. Kirkinis, A. V. Andreev, and B. Spivak
We introduce a new mechanism for the propulsion and separation by chirality of small ferromagnetic particles suspended in a liquid. Under the action of a uniform dc magnetic field H and an ac electric field E isomers with opposite chirality move in opposite directions. Such a mechanism could have a ... [Phys. Rev. E 85, 016321 ] published .

Surface-charge-induced alteration of nanovortex patterning in nanoscale confinements with patterned wettability gradients

Manik Mayur, Debapriya Chakraborty, Jeevanjyoti Chakraborty, and Suman Chakraborty
We characterize the generation of flow vortices in nanoscale confinements under the combined effects of patterned surface charge density and substrate wettability. Using molecular dynamics simulations, we elucidate the effects of ion solvation and steric interactions toward influencing the resultant ... [Phys. Rev. E 85, 016315 ] published .

Synchronous imaging for rapid visualization of complex vibration profiles in electromechanical microresonators

Yoav Linzon, Daniel J. Joe, Bojan Ilic, Juraj Topolancik, Jeevak M. Parpia et al.
Synchronous imaging is used for the dynamic space-domain studies of vibration profiles in capacitively driven, thin n + doped polysilicon microbridges oscillating at rf frequencies. Fast and high-resolution actuation profile measurements of micromachined resonators are useful when significant device ... [J. Appl. Phys. 111, 023507 (2012)] published Fri Jan 20, 2012.

Nonlinear detection mechanism in quantitative atomic force microscopy characterization of high-frequency nanoelectromechanical systems

Marc Serra-Garcia, Francesc Perez-Murano, and Alvaro San Paulo
We investigate the transduction of motion from a nanomechanical resonator to the cantilever/tip probe of an atomic force microscope. Our results show that amplitude-modulated high-frequency vibrations of nanomechanical resonators can be measured by means of a low-resonance frequency cantilever as a ... [Phys. Rev. B 85, 035433 ] published .

Observation of Quantum Motion of a Nanomechanical Resonator

Amir H. Safavi-Naeini, Jasper Chan, Jeff T. Hill, Thiago P. Mayer Alegre, Alex Krause et al.
In this Letter we use resolved sideband laser cooling to cool a mesoscopic mechanical resonator to near its quantum ground state (phonon occupancy 2.60.2), and observe the motional sidebands generated on a second probe laser. Asymmetry in the sideband amplitudes provides a direct measure of the disp ... [Phys. Rev. Lett. 108, 033602 ] published .

Parabolic tapered photonic crystal cavity in silicon

Boris Desiatov, Ilya Goykhman, and Uriel Levy
We demonstrate the design, fabrication, transmission spectrum measurement, and near-field characterization of a parabolic tapered one-dimensional photonic crystal cavity in silicon. The results shows a relatively high quality factor (~43 000), together with a small modal volume of ~1.1(lambda/n). Mo ... [Appl. Phys. Lett. 100, 041112 (2012)] published Wed Jan 25, 2012.

Room temperature, continuous wave lasing in microcylinder and microring quantum dot laser diodes

M. Munsch, J. Claudon, N. S. Malik, K. Gilbert, P. Grosse et al.
We demonstrate room temperature, continuous wave lasing of laser diodes based on AlGaAs whispering gallery mode (WGM) resonators (microcylinder and microring) embedding a quantum dot (QD) active layer. Using InGaAlAs QDs, high-Q (>60 000) lasing modes are observed around 910 nm, up to 50 degrees C. ... [Appl. Phys. Lett. 100, 031111 (2012)] published Fri Jan 20, 2012.

Spiral plasmonic nanoantennas as circular polarization transmission filters

K. A. Bachman, J. J. Peltzer, P. D. Flammer, T. E. Furtak, R. T. Collins et al.
We present simulation and experimental results for easily fabricated spiral plasmonic antenna analogues providing circular polarization selectivity. One circular polarization state is concentrated and transmitted through a subwavelength aperture, while the opposite circular state is blocked. The spe ... [Opt. Express 20, 1308 (2012)] published Tue Jan 24, 2012.

Enhancement of local electromagnetic fields in plasmonic crystals of coaxial metallic nanostructures

Masanobu Iwanaga, Naoki Ikeda, and Yoshimasa Sugimoto
We have experimentally and numerically examined resonant modes in plasmonic crystals (PlCs) of coaxial metallic nanostructures. Resonance enhancements of local electromagnetic (EM) fields were evaluated quantitatively. We clarified that a local mode induced in the coaxial metallic structure shows th ... [Phys. Rev. B 85, 045427 ] published .

Mapping between quantum dot and quantum well lasers: From conventional to spin lasers

Jeongsu Lee, Rafal Oszwaldowski, Christian Gothgen, and Igor Zutic
We explore similarities between the quantum wells and quantum dots used as optical gain media in semiconductor lasers. We formulate a mapping procedure which allows a simpler, often analytical, description of quantum well lasers to study more complex lasers based on quantum dots. The key observation ... [Phys. Rev. B 85, 045314 ] published .

Electron spin synchronization induced by optical nuclear magnetic resonance feedback

M. M. Glazov, I. A. Yugova, and Al. L. Efros
We predict a new physical mechanism to explain the electron spin precession frequency focusing effect recently observed in singly charged quantum dots exposed to a periodic train of resonant circularly polarized short optical pulses [A. Greilich et al., Science 317, 1896 (2007)]. We show that electr ... [Phys. Rev. B 85, 041303 ] published .

Proposed isotropic negative index in three-dimensional optical metamaterials

Boubacar Kante, Kevin O'Brien, Avi Niv, Xiaobo Yin, and Xiang Zhang
A simple route toward achieving an isotropic optical negative index in three dimensions is theoretically proposed. We show that, in contrast with previous studies, the plasmonic ring resonators, symmetrically split with an odd number of gaps, have both degenerate electric and magnetic resonances and ... [Phys. Rev. B 85, 041103 ] published .

Mesoscopic Self-Collimation and Slow Light in All-Positive Index Layered Photonic Crystals

Julien Arlandis, Emmanuel Centeno, Remi Polles, Antoine Moreau, Julien Campos et al.
We demonstrate a mesoscopic self-collimation effect in photonic crystal superlattices consisting of a periodic set of all-positive index 2D photonic crystal and homogeneous layers. We develop an electromagnetic theory showing that diffraction-free beams are observed when the curvature of the optical ... [Phys. Rev. Lett. 108, 037401 ] published .

Backscattering Suppression in Supersonic 1D Polariton Condensates

D. Tanese, D. D. Solnyshkov, A. Amo, L. Ferrier, E. Bernet-Rollande et al.
We investigate the effect of disorder on the propagation of one-dimensional polariton condensates in semiconductor microcavities. We observe a strong suppression of the backscattering produced by the imperfections of the structure when increasing the condensate density. This suppression occurs in th ... [Phys. Rev. Lett. 108, 036405 ] published .

Ultrafast Tilting of the Dispersion of a Photonic Crystal and Adiabatic Spectral Compression of Light Pulses

Daryl M. Beggs, Thomas F. Krauss, L. Kuipers, and Tobias Kampfrath
We demonstrate, by theory and experiment, the ultrafast tilting of the dispersion curve of a photonic-crystal waveguide following the absorption of a femtosecond pump pulse. By shaping the pump-beam cross section with a nanometric shadow mask, different waveguide eigenmodes acquire different spatial ... [Phys. Rev. Lett. 108, 033902 ] published .

Genetic-Algorithm Discovery of a Direct-Gap and Optically Allowed Superstructure from Indirect-Gap Si and Ge Semiconductors

Mayeul d'Avezac, Jun-Wei Luo, Thomas Chanier, and Alex Zunger
Combining two indirect-gap materialswith different electronic and optical gapsto create a direct gap material represents an ongoing theoretical challenge with potentially rewarding practical implications, such as optoelectronics integration on a single wafer. We provide an unexpected solution to thi ... [Phys. Rev. Lett. 108, 027401 ] published .

Broadband Light Harvesting Nanostructures Robust to Edge Bluntness

Yu Luo, Dang Yuan Lei, Stefan A. Maier, and J. B. Pendry
Metallic structures with sharp corners harvest the energy of incident light through plasmonic resonances, concentrating it in the corners and greatly increasing the local energy density. Despite its wide array of applications, this effect is normally strongly dependent on how sharp the corners are, ... [Phys. Rev. Lett. 108, 023901 ] published .

Broadband Light Bending with Plasmonic Nanoantennas

Xingjie Ni, Naresh K. Emani, Alexander V. Kildishev, Alexandra Boltasseva, and Vladimir M. Shalaev
The precise manipulation of a propagating wave using phase control is a fundamental building block of optical systems. The wavefront of a light beam propagating across an interface can be modified arbitrarily by introducing abrupt phase changes. We experimentally demonstrated unparalleled wavefront ... [Science 335, 427 (2012)] published Tue Jan 24, 2012.

An All-Silicon Passive Optical Diode

Li Fan, Jian Wang, Leo T. Varghese, Hao Shen, Ben Niu et al.
A passive optical diode effect would be useful for on-chip optical information processing but has been difficult to achieve. Using a method based on optical nonlinearity, we demonstrate a forward-backward transmission ratio of up to 28 decibels within telecommunication wavelengths. Our device, which ... [Science 335, 447 (2012)] published Tue Jan 24, 2012.

Scanning probe microscopy imaging of metallic nanocontacts

D. Stoffler, S. Fostner, P. Grutter, and R. Hoffmann-Vogel
We show scanning probe microscopy measurements of metallic nanocontacts between controlled electromigration cycles. The nanowires used for the thinning process are fabricated by shadow evaporation. The highest resolution obtained using scanning force microscopy is about 3 nm. During the first few el ... [Phys. Rev. B 85, 033404 ] published .

Magnetic study of CuMnO (0 <= x <= 0.08) nanoparticles

Shahzad Hussain, A. Mumtaz, S. K. Hasanain, and M. Usman
CuMnO (0 <= x <= 0.08) nanoparticles were synthesized by a coprecipitation method. Powder x ray analysis reveals that samples show a pure CuO phase for x <= 0.06 and the appearance of a secondary phase CuMnO for x > 0.06. The unit cell volume expands with increasing Mn concentration up to x = 0.06 a ... [J. Appl. Phys. 111, 023908 (2012)] published Mon Jan 23, 2012.

Spin transport in memristive devices

Hyuk-Jae Jang, Oleg A. Kirillov, Oana D. Jurchescu, and Curt A. Richter
We report on electron spin transport through electrochemically precipitated copper filaments formed in TaO memristive devices consisting of Co/TaO/Cu/Py with crossbar-type electrode geometry. The devices show memristive behavior having a typical OFF/ON resistance ratio of 10. Magnetoresistance measu ... [Appl. Phys. Lett. 100, 043510 (2012)] published Thu Jan 26, 2012.

Temperature evolution of spin accumulation detected electrically in a nondegenerated silicon channel

Y. Ando, K. Kasahara, S. Yamada, Y. Maeda, K. Masaki et al.
We study temperature evolution of spin-accumulation signals obtained by the three-terminal Hanle-effect measurements in a nondegenerated silicon channel with a Schottky-tunnel-barrier contact. We find the clear difference in the temperature-dependent spin signals between spin-extraction and spin-inj ... [Phys. Rev. B 85, 035320 ] published .

Nanoscale inhomogeneities: A new path toward high Curie temperature ferromagnetism in diluted materials

Akash Chakraborty, Richard Bouzerar, Stefan Kettemann, and Georges Bouzerar
Room-temperature ferromagnetism has been one of the most sought after topics in today's emerging field of spintronics. It is strongly believed that defect- and inhomogeneity-free sample growth should be the optimal route for achieving room-temperature ferromagnetism, and huge efforts are made in ord ... [Phys. Rev. B 85, 014201 ] published .

Tunable Resistivity of Individual Magnetic Domain Walls

J. H. Franken, M. Hoeijmakers, H. J. M. Swagten, and B. Koopmans
Despite the relevance of current-induced magnetic domain wall (DW) motion for new spintronics applications, the exact details of the current-domain wall interaction are not yet understood. A property intimately related to this interaction is the intrinsic DW resistivity. Here, we investigate experim ... [Phys. Rev. Lett. 108, 037205 ] published .

Transverse focusing of spin-polarized photocurrents

Juerong Li, A. M. Gilbertson, K. L. Litvinenko, L. F. Cohen, and S. K. Clowes
We measure transverse magnetically focused photocurrent signals in an InSb/InAlSb quantum well device. Using optical spin orientation by modulated circularly polarized light an electron spin-dependent signal is observed due to the spin-orbit interaction. Simulations of the focusing signal are perfor ... [Phys. Rev. B 85, 045431 ] published .

Magnetization dynamics and cone angle precession in permalloy rectangles

Nils Kuhlmann, Andreas Vogel, and Guido Meier
Magnetization dynamics in pairs of submicrometer-sized permalloy rectangles are studied by means of broadband-ferromagnetic resonance measurements. The coupling strength of neighboring elements depends on their center-to-center distance. The stray field of one rectangle decreases the local effective ... [Phys. Rev. B 85, 014410 ] published .

Symmetry and nonstoichiometry as possible origins of ferromagnetism in nanoscale oxides

Takashi Uchino and Toshinobu Yoko
We show through density functional theory calculations that extended magnetic states can inherently occur in oxides as the size of the crystals is reduced down to the nanometer scale. In nanoscale systems, some crystallographically perfect MgO crystallites paradoxically result in nonstoichiometric c ... [Phys. Rev. B 85, 012407 ] published .

Emergent phenomena at oxide interfaces

H. Y. Hwang, Y. Iwasa, M. Kawasaki, B. Keimer, N. Nagaosa et al.
Recent technical advances in the atomic-scale synthesis of oxide heterostructures have provided a fertile new ground for creating novel states at their interfaces. Different symmetry constraints can be used to design structures exhibiting phenomena not found in the bulk constituents. A characteristi ... [Nature Mater. 11, 103 (2012)] published Thu Jan 26, 2012.

Shot noise induced by electron-nuclear spin-flip scattering in a nonequilibrium quantum wire

Kensaku Chida, Masayuki Hashisaka, Yoshiaki Yamauchi, Shuji Nakamura, Tomonori Arakawa et al.
We study the shot noise (nonequilibrium current fluctuation) associated with dynamic nuclear polarization in a nonequilibrium quantum wire (QW) fabricated in a two-dimensional electron gas. We observe that the spin-polarized conductance quantization of the QW in the integer quantum Hall regime colla ... [Phys. Rev. B 85, 041309 ] published .

Measurement of a Pauli and Orbital Paramagnetic State in Bulk Gold Using X-Ray Magnetic Circular Dichroism Spectroscopy

Motohiro Suzuki, Naomi Kawamura, Hayato Miyagawa, Jose S. Garitaonandia, Yoshiyuki Yamamoto et al.
We show that bulk gold (Au) exhibits temperature-independent paramagnetism in an external magnetic field by x-ray magnetic circular dichroism spectroscopy at the Au L and L edges. Using the sum-rule analysis, we obtained a magnetic moment of 1.3 x 10 [mu]/atom in an external magnetic field of 10 T ... [Phys. Rev. Lett. 108, 047201 ] published .

Magnetism in nanometer-thick magnetite

Matteo Monti, Benito Santos, Arantzazu Mascaraque, Oscar Rodriguez de la Fuente, Miguel Angel Nino et al.
The oldest known magnetic material, magnetite, is of current interest for use in spintronics as a thin film. An open question is how thin can magnetite films be and still retain the robust ferrimagnetism required for many applications. We have grown 1-nm-thick magnetite crystals and characterized th ... [Phys. Rev. B 85, 020404 ] published .

Topological Hubbard Model and Its High-Temperature Quantum Hall Effect

Titus Neupert, Luiz Santos, Shinsei Ryu, Claudio Chamon, and Christopher Mudry
The quintessential two-dimensional lattice model that describes the competition between the kinetic energy of electrons and their short-range repulsive interactions is the repulsive Hubbard model. We study a time-reversal symmetric variant of the repulsive Hubbard model defined on a planar lattice: ... [Phys. Rev. Lett. 108, 046806 ] published .

Quantum phase transitions in ultrathin films of three-dimensional topological insulators in the presence of an electrostatic potential and a Zeeman field

Huichao Li, L. Sheng, and D. Y. Xing
We investigate transport properties of the surface states of three-dimensional topological insulator thin films in the presence of an electrostatic potential gamma and a spin-splitting Zeeman field g. It is shown that there exist a quantum pseudospin Hall phase, a quantum anomalous Hall phase, and a ... [Phys. Rev. B 85, 045118 ] published .

Signature of interaction in dc transport of ac-gated quantum spin Hall edge states

Fabrizio Dolcini
In the presence of a scattering potential, electron transport in a quantum wire is known to be dramatically modified by backward-scattering and unaffected by forward-scattering processes. We show that the scenario is quite different in quantum spin Hall edge states coupled at a constriction. The hel ... [Phys. Rev. B 85, 033306 ] published .

Hydrodynamic rectified drag current in a quantum wire induced by Wigner crystallization

M. Yamamoto, H. Takagi, M. Stopa, and S. Tarucha
We measure Coulomb drag between displaced parallel quantum wires fabricated on a high-mobility two-dimensional electron gas using a split-gate technique. We observe a rectified Coulomb drag, in which the sign of the drag current is the same irrespective of the current direction in the drive wire, wh ... [Phys. Rev. B 85, 041308 ] published .

Single-Shot Measurement of Triplet-Singlet Relaxation in a Si/SiGe Double Quantum Dot

J. R. Prance, Zhan Shi, C. B. Simmons, D. E. Savage, M. G. Lagally et al.
We investigate the lifetime of two-electron spin states in a few-electron Si/SiGe double dot. At the transition between the (1,1) and (0,2) charge occupations, Pauli spin blockade provides a readout mechanism for the spin state. We use the statistics of repeated single-shot measurements to extract t ... [Phys. Rev. Lett. 108, 046808 ] published .

Enhancement of the Kondo Effect through Rashba Spin-Orbit Interactions

Mahdi Zarea, Sergio E. Ulloa, and Nancy Sandler
We study a one-orbital Anderson impurity in a two-dimensional electron bath with Rashba spin-orbit interactions in the Kondo regime. The spin SU(2) symmetry-breaking term couples the impurity to a two-band electron gas. A Schrieffer-Wolff transformation shows the existence of the Dzyaloshinsky-Moriy ... [Phys. Rev. Lett. 108, 046601 ] published .

Transmission Eigenvalues and the Bare Conductance in the Crossover to Anderson Localization

Zhou Shi and Azriel Z. Genack
We measure the field transmission matrix t for microwave radiation propagating through random waveguides in the crossover to Anderson localization. From these measurements, we determine the dimensionless conductance g and the individual eigenvalues tau of the transmission matrix tt whose sum equals ... [Phys. Rev. Lett. 108, 043901 ] published .

Cold-Field Switching in PVDF-TrFE Ferroelectric Polymer Nanomesas

Igor Stolichnov, Peter Maksymovych, Evgeny Mikheev, Sergei V. Kalinin, Alexander K. Tagantsev et al.
Polarization reversal in ferroelectric nanomesas of polyvinylidene fluoride with trifluoroethylene has been probed by ultrahigh vacuum piezoresponse force microscopy in a wide temperature range from 89 to 326 K. In dramatic contrast to the macroscopic data, the piezoresponse force microscopy local s ... [Phys. Rev. Lett. 108, 027603 ] published .

Spin-dependent avoided-crossing effect on quantum-well states in Al/W(110)

A. G. Rybkin, A. M. Shikin, D. Marchenko, A. Varykhalov, and O. Rader
Despite their low atomic number, Al films show large spin-orbit splittings when grown on W(110). Our spin- and angle-resolved photoemission experiment reveals two types of spin-orbit split states: quantum-well states (QWSs) with small Rashba splitting proportional to the electron wave vector in the ... [Phys. Rev. B 85, 045425 ] published .

Experimental evidence for Luttinger liquid behavior in sufficiently long GaAs V-groove quantum wires

E. Levy, I. Sternfeld, M. Eshkol, M. Karpovski, B. Dwir et al.
We have measured the temperature dependence of the conductance of long V-groove quantum wires fabricated using GaAs/AlGaAs heterostructures, in a wide temperature range (200 mK

Phonon-assisted relaxation between hole states in quantum dot molecules

Krzysztof Gawarecki and Pawel Machnikowski
We study theoretically phonon-assisted relaxation and inelastic tunneling of holes in a double quantum dot. We derive hole states and relaxation rates from kp Hamiltonians and show that there is a finite distance between the dots where lifetimes of hole states are very long, which is related to vani ... [Phys. Rev. B 85, 041305 ] published .

Signatures of Rashba spin-orbit interaction in the superconducting proximity effect in helical Luttinger liquids

Pauli Virtanen and Patrik Recher
We consider the superconducting proximity effect in a helical Luttinger liquid at the edge of a two-dimensional (2D) topological insulator, and derive the low-energy Hamiltonian for an edge state tunnel-coupled to an s-wave superconductor. In addition to correlations between the left- and right-movi ... [Phys. Rev. B 85, 035310 ] published .

Nonadiabatic electron pumping through interacting quantum dots

Alexander Croy, Ulf Saalmann, Alexis R. Hernandez, and Caio H. Lewenkopf
We study nonadiabatic charge pumping through single-level quantum dots taking into account Coulomb interactions. We show how a truncated set of equations of motion can be propagated in time by means of an auxiliary-mode expansion. This formalism is capable of treating time-dependent electronic trans ... [Phys. Rev. B 85, 035309 ] published .

Hybridization of wave functions in one-dimensional localization

D. A. Ivanov, M. A. Skvortsov, P. M. Ostrovsky, and Ya. V. Fominov
A quantum particle can be localized in a disordered potential, the effect known as Anderson localization. In such a system, correlations of wave functions at very close energies may be described, due to Mott, in terms of a hybridization of localized states. We revisit this hybridization description ... [Phys. Rev. B 85, 035109 ] published .

Localization and mobility gap in the topological Anderson insulator

Yan-Yang Zhang, Rui-Lin Chu, Fu-Chun Zhang, and Shun-Qing Shen
It has been proposed that disorder may lead to a new type of topological insulator, called the topological Anderson insulator (TAI). Here we examine the physical origin of this phenomenon. We calculate the topological invariants and density of states of the disordered model in a supercell of a two-d ... [Phys. Rev. B 85, 035107 ] published .

Probing the spin states of three interacting electrons in quantum dots

A. Gamucci, V. Pellegrini, A. Singha, A. Pinczuk, L. N. Pfeiffer et al.
We observe a low-lying sharp spin mode of three interacting electrons in an array of nanofabricated AlGaAs/GaAs quantum dots by means of resonant inelastic light scattering. The finding is enabled by a suppression of the inhomogeneous contribution to the excitation spectra obtained by reducing the n ... [Phys. Rev. B 85, 033307 ] published .

Effects of fermion flavor on exciton condensation in double-layer systems

J. Shumway and Matthew J. Gilbert
We use a fermionic path-integral quantum Monte Carlo framework to study the effects of fermion flavor on the physical properties of dipolar exciton condensates in double-layer systems. We find that by including spin in the system the effective interlayer interaction strength is weakened, yet this ha ... [Phys. Rev. B 85, 033103 ] published .

Conductance fluctuations in chaotic systems with tunnel barriers

Daniel Waltner, Jack Kuipers, Philippe Jacquod, and Klaus Richter
Quantum effects are expected to disappear in the short-wavelength, semiclassical limit. As a matter of fact, recent investigations of transport through quantum chaotic systems have demonstrated the exponential suppression of the weak localization corrections to the conductance and of the Fano factor ... [Phys. Rev. B 85, 024302 ] published .

Vanishing quasiparticle density in a hybrid Al/Cu/Al single-electron transistor

O.-P. Saira, A. Kemppinen, V. F. Maisi, and J. P. Pekola
The achievable fidelity of many nanoelectronic devices based on superconducting aluminum is limited by either the density of residual nonequilibrium quasiparticles n or the density of quasiparticle states in the gap, characterized by Dynes parameter gamma. We infer upper bounds n<0.033 [mu]m and ga ... [Phys. Rev. B 85, 012504 ] published .

Real-time simulation of finite-frequency noise from a single-electron emitter

T. Jonckheere, T. Stoll, J. Rech, and T. Martin
We study the real-time emission of single electrons from a quantum dot coupled to a one dimensional conductor, using exact diagonalization on a discrete tight-binding chain. We show that, from the calculation of the time evolution of the one-electron states, we have simple access to all the relevant ... [Phys. Rev. B 85, 045321 ] published .

General method for calculating the universal conductance of strongly correlated junctions of multiple quantum wires

Armin Rahmani, Chang-Yu Hou, Adrian Feiguin, Masaki Oshikawa, Claudio Chamon et al.
We develop a method to extract the universal conductance of junctions of multiple quantum wires, a property of systems connected to reservoirs, from static ground-state computations in closed finite systems. The method is based on a key relationship, derived within the framework of boundary conforma ... [Phys. Rev. B 85, 045120 ] published .

Quantized nu=5/2 State in a Two-Subband Quantum Hall System

J. Nuebler, B. Friess, V. Umansky, B. Rosenow, M. Heiblum et al.
The evolution of the fractional quantum Hall state at filling 5/2 is studied in density tunable two-dimensional electron systems formed in wide wells in which it is possible to induce a transition from single- to two-subband occupancy. In 80 and 60 nm wells, the quantum Hall state at 5/2 filling of ... [Phys. Rev. Lett. 108, 046804 ] published .

Coherent singlet-triplet oscillations in a silicon-based double quantum dot

B. M. Maune, M. G. Borselli, B. Huang, T. D. Ladd, P. W. Deelman et al.
Silicon is more than the dominant material in the conventional microelectronics industry: it also has potential as a host material for emerging quantum information technologies. Standard fabrication techniques already allow the isolation of single electron spins in silicon transistor-like devices. ... [Nature 481, 344 (2012)] published Fri Jan 20, 2012.

Gating the Charge State of Single Molecules by Local Electric Fields

I. Fernandez-Torrente, D. Kreikemeyer-Lorenzo, A. Strozecka, K. J. Franke, and J. I. Pascual
The electron-acceptor molecule TCNQ is found in either of two distinct integer charge states when embedded into a monolayer of a charge transfer complex on a gold surface. Scanning tunneling spectroscopy measurements identify these states through the presence or absence of a zero-bias Kondo resonanc ... [Phys. Rev. Lett. 108, 036801 ] published .

Electron-phonon scattering in topological insulator thin films

Sebastien Giraud, Arijit Kundu, and Reinhold Egger
We present a theoretical study of electron-phonon scattering effects in thin films made of a strong topological insulator. The phonons are modeled by isotropic elastic continuum theory with stress-free boundary conditions, and the interaction with the helical surface Dirac fermions is mediated by th ... [Phys. Rev. B 85, 035441 ] published .

Growth sector dependence and mechanism of stress formation in epitaxial diamond growth

M. Fischer, S. Gsell, M. Schreck, and A. Bergmaier
Stress generation in epitaxial diamond growth was investigated by [mu]-Raman spectroscopy and high resolution x-ray diffraction. Intrinsic stress could be varied systematically from compressive to tensile covering a huge range of 5 GPa. The temperature-stress curve for growth on {111}-sectors as com ... [Appl. Phys. Lett. 100, 041906 (2012)] published Thu Jan 26, 2012.

Why Nanoprojectiles Work Differently than Macroimpactors: The Role of Plastic Flow

Christian Anders, Eduardo M. Bringa, Gerolf Ziegenhain, Giles A. Graham, J. Freddy Hansen et al.
Atomistic simulation data on crater formation due to the hypervelocity impact of nanoprojectiles of up to 55 nm diameter and with targets containing up to 1.1 x 10 atoms are compared to available experimental data on [mu]m-, mm-, and cm-sized projectiles. We show that previous scaling laws do not ho ... [Phys. Rev. Lett. 108, 027601 ] published .

Confinement effects on the vibrational properties of III-V and II-VI nanoclusters

Peng Han and Gabriel Bester
We present a first-principles study of the confinement effects on the vibrational properties of thousand atoms (radii up to 16.2 A) colloidal III-V and II-VI nanoclusters. We describe how the molecular-type vibrations, such as surface-optical, surface-acoustic, and coherent acoustic modes, coexist a ... [Phys. Rev. B 85, 041306 ] published .

Gallium-droplet behaviors of self-catalyzed GaAs nanowires: A transmission electron microscopy study

Young Heon Kim, Dong Woo Park, and Sang Jun Lee
When the arsenic (As) precursor was supplied during cool down, the gallium (Ga) droplets on top of GaAs nanowires (NWs) were extinct on the final products. The Ga droplets were conserved, and their behaviors depended on the size of the NWs when the As supply was cut off during the cooling: The conta ... [Appl. Phys. Lett. 100, 033117 (2012)] published Fri Jan 20, 2012.

Direct patterning of functional interfaces in oxide heterostructures

N. Banerjee, M. Huijben, G. Koster, and G. Rijnders
We report on the direct patterning of high-quality structures incorporating the LaAlO-SrTiO interface by an epitaxial-liftoff technique avoiding any reactive ion beam etching. Detailed studies of temperature dependent magnetotransport properties were performed on the patterned heterostructures with ... [Appl. Phys. Lett. 100, 041601 (2012)] published Mon Jan 23, 2012.

Colloquium: Stimulating uncertainty: Amplifying the quantum vacuum with superconducting circuits

P. D. Nation, J. R. Johansson, M. P. Blencowe, and Franco Nori
The ability to generate particles from the quantum vacuum is one of the most profound consequences of Heisenberg's uncertainty principle. Although the significance of vacuum fluctuations can be seen throughout physics, the experimental realization of vacuum amplification effects has until now been l ... [Rev. Mod. Phys. 84, 1 ] published .