Virtual Journal of Nanoscale Science & Technology

Monte Carlo studies of the intrinsic time-domain response of nanoscale three-branch junctions

I. Iniguez-de-la-Torre, H. Rodilla, J. Mateos, T. Gonzalez, H. Irie et al.
We present a Monte Carlo time-domain study of nanostructured ballistic three-branch junctions (TBJs) excited by both step-function and Gaussian picosecond transients. Our TBJs were based on InGaAs 2-dimensional electron gas heterostructures and their geometry followed exactly the earlier experimenta ... [J. Appl. Phys. 111, 084511 (2012)] published Fri Apr 27, 2012.

The photoionization cross section of a hydrogenic impurity in a multi-layered spherical quantum dot

Mehmet Şahin, Firdes Tek, and Ahmet Erdinc
In this study, we have investigated the photoionization cross section of an on-center hydrogenic impurity in a multi-layered spherical quantum dot. The electronic energy levels and their wave functions have been determined fully numerically by shooting method. Also, we have calculated the binding en ... [J. Appl. Phys. 111, 084317 (2012)] published Fri Apr 27, 2012.

Chemisorption on semiconductors: The role of quantum corrections on the space charge regions in multiple dimensions

Francesco Ciucci, Carlo de Falco, Marcelo I. Guzman, Sara Lee, and Tomonori Honda
The chemisorption of O on nanoscale n-doped CdS semiconductors is computed in terms of a Wolkenstein isotherm coupled to the Schrodinger Poisson equation. Present numerical results show the dependence of the chemisorbed charge and the differential capacitance on oxygen partial pressure. A comparison ... [Appl. Phys. Lett. 100, 183106 (2012)] published Thu May 3, 2012.

Dynamic observations of dislocation behavior in SrTiO by in situ nanoindentation in a transmission electron microscope

Shun Kondo, Naoya Shibata, Tasuku Mitsuma, Eita Tochigi, and Yuichi Ikuhara
The plastic deformation process of a SrTiO single crystal has been dynamically and microscopically observed by in situ nanoindentation in a transmission electron microscope. The plastic deformation of SrTiO was found to proceed by dislocation slips even at room temperatures under the present experim ... [Appl. Phys. Lett. 100, 181906 (2012)] published Thu May 3, 2012.

Experiment and theoretical modeling of the luminescence of silver nanoclusters dispersed in oxyfluoride glass

Ngo T. Cuong, Victor K. Tikhomirov, Liviu F. Chibotaru, Andre Stesmans, Vicente D. Rodriguez et al.
Density functional theory (DFT) and complete active space perturbation theory (CASPT2) have been applied for modeling the configuration, charge, energy states, and spin of luminescent Ag nanoclusters dispersed within the bulk of oxyfluoride glass host. The excitation spectra of luminescence of the A ... [J. Chem. Phys. 136, 174108 (2012)] published Thu May 3, 2012.

Engineering surface waves in flat phononic plates

Hector Estrada, Pilar Candelas, Francisco Belmar, Antonio Uris, F. Javier Garcia de Abajo et al.
Surface acoustic-wave phenomena span a wide range of length scales going from the devastation of earthquakes down to image reconstruction of buried nanostructures. In solid-fluid systems, the so-called Scholte-Stoneley waves (SSWs) dominate the scene at the interface with their evanescent fields dec ... [Phys. Rev. B 85, 174301 ] published .

Influence of retardation in the scattering of ultracold atoms by conducting nanowires

Martin Fink, Johannes Eiglsperger, Javier Madronero, and Harald Friedrich
We study low-energy scattering of a neutral atom by a perfectly conducting cylindrical nanowire. Based on the exact atom-wire potential given recently by Eberlein and Zietal [Phys. Rev. A 80, 012504 (2009)] we derive tractable expressions for both the nonretarded van der Waals limit and the highly r ... [Phys. Rev. A 85, 040702 ] published .

Comparative analysis of photoluminescence and Raman enhancement by metal nanoparticles

Greg Sun, Jacob B. Khurgin, and Din Ping Tsai
We present a comparative study on the enhancement of photoluminescence and Raman processes by a single metal nanoparticle. Taking an analytical approach, we show the physics behind strikingly different orders of magnitude in enhancement that have been observed, provide fundamental explanation for no ... [Opt. Lett. 37, 1583 (2012)] published Thu May 3, 2012.

Ultralow-refractive-index optical thin films through nanoscale etching of ordered mesoporous silica films

Fangting Chi, Lianghong Yan, Hongwei Yan, Bo Jiang, Haibing Lv et al.
A great deal of intensive research has been conducted to obtain high-quality transparent ultralow-refractive-index and ultralow-dielectric-constant thin films for microptics and microelectronics applications. Here, we report a simple procedure to prepare highly porous silica thin films with high opt ... [Opt. Lett. 37, 1406 (2012)] published Thu May 3, 2012.

Observing the localization of light in space and time by ultrafast second-harmonic microscopy

Manfred Mascheck, Slawa Schmidt, Martin Silies, Takashi Yatsui, Kokoro Kitamura et al.
Multiple coherent scattering and the constructive interference of certain scattering paths form the common scheme of several remarkable localization phenomena of classical and quantum waves in randomly disordered media. Prominent examples are electron transport in disordered conductors, the localiza ... [Nat. Photonics 6, 293 (2012)] published Wed May 2, 2012.

A microfluidics approach towards high-throughput pathogen removal from blood using margination

Han Wei Hou, Hiong Yap Gan, Ali Asgar S. Bhagat, Leon D. Li, Chwee Teck Lim et al.
Sepsis is an adverse systemic inflammatory response caused by microbial infection in blood. This paper reports a simple microfluidic approach for intrinsic, non-specific removal of both microbes and inflammatory cellular components (platelets and leukocytes) from whole blood, inspired by the invivo ... [Biomicrofluidics 6, 024115 (2012)] published Tue May 1, 2012.

Thermally stable polymer composites with improved transparency by using colloidal mesoporous silica nanoparticles as inorganic fillers

Norihiro Suzuki, Mohamed B. Zakaria, Ya-Dong Chiang, Kevin C.-W. Wu, and Yusuke Yamauchi
The colloidal mesoporous silica nanoparticles with small particle sizes (namely, CMS) are used as inorganic fillers of polymers (i.e. epoxy and silicone). From simple calculation, almost all polymers are estimated to be confined in the mesopores. To clarify the superiority of CMS over nonporous sili ... [Phys. Chem. Chem. Phys. 14, 7427 (2012)] published Thu May 3, 2012.

Impurity-assisted Andreev reflection at a spin-active half metal-superconductor interface

Francis B. Wilken and Piet W. Brouwer
The Andreev reflection amplitude at a clean interface between a half-metallic ferromagnet (H) and a superconductor (S) for which the half metal's magnetization has a gradient perpendicular to the interface is proportional to the excitation energy [eh] and vanishes at [eh]=0 [Beri et al., Phys. Rev. ... [Phys. Rev. B 85, 134531 ] published .

Ordering Mechanisms in Epitaxial SiGe Nanoislands

G. Vantarakis, I. N. Remediakis, and P. C. Kelires
We investigate and elucidate the surprising observation of atomically ordered domains in dome-shaped SiGe nanoislands. We show, through atomistic Monte Carlo simulations, that this ordering is a surface-related phenomenon, and that is driven by surface equilibrium rather than by surface kinetics. Th ... [Phys. Rev. Lett. 108, 176102 ] published .

Nanocrystalline hybrid inorganicorganic one-dimensional chain systems tailored with 2- and 3-phenyl ring monocarboxylic acids

Igor Djerdj, Jasminka Popovic, Jernej Stare, Gabriela AmbroZiC, SreCo D. Skapin et al.
Two novel nanosized hybrid inorganicorganic frameworks, VO(CHCOO), and VO(CHCOO) have been solvothermally synthesized and their structures elucidated using a combination of powder XRD and DFT geometry optimization. They contain one-dimensional chains of corner-sharing tetrahedra in the case of VO(CH ... [J. Mater. Chem. 22, 10255 (2012)] published Thu May 3, 2012.

Comparison of scattering and reflection SFG: a question of phase-matching

Hilton B. de Aguiar, Rudiger Scheu, Kailash C. Jena, Alex G. F. de Beer, and Sylvie Roke
We present a comparison between sum frequency scattering (SFS) and reflection mode sum frequency generation (R-SFG). We have used scattering theory to describe both scattering experiments as well as reflection mode experiments. The interfacial vibrational spectrum of nanoscopic oil droplets disperse ... [Phys. Chem. Chem. Phys. 14, 6826 (2012)] published Thu May 3, 2012.

Facile synthesis of metalorganic framework films via in situ seeding of nanoparticles

Dongmei Jiang, Andrew D. Burrows, Robben Jaber, and Karen J. Edler
A facile in situ nanoparticle seeding method is reported to prepare MIL-101(Cr) films on alumina supports. The in situ seeding of MIL-101(Cr) nanoparticles was promoted by use of dimethylacetamide (DMA). The generality of this approach is further demonstrated for Cu(btc) films by using a (poly)acryl ... [Chem. Commun. 48, 4965 (2012)] published Thu May 3, 2012.

Nonvolatile floating gate organic memory device based on pentacene/CdSe quantum dot heterojuction

Ik-Soo Shin, Jung-Min Kim, Jun-Ho Jeun, Seok-Hyun Yoo, Ziyi Ge et al.
An organic floating-gate memory device using CdSe quantum dots (QDs) as a charge-trapping element was fabricated. CdSe QDs were localized beneath a pentacene without any tunneling insulator, and the QD layer played a role as hole-trapping sites. The band bending formed at the junction between pentac ... [Appl. Phys. Lett. 100, 183307 (2012)] published Thu May 3, 2012.

Photoresponse of PbS nanoparticlesquaterthiophene films prepared by gaseous deposition as probed by XPS

Michael W. Majeski, F. Douglas Pleticha, Igor L. Bolotin, Luke Hanley, Eda Yilmaz et al.
Semiconducting lead sulfide (PbS) nanoparticles were cluster beam deposited into evaporated quaterthiophene (4T) organic films, which in some cases were additionally modified by simultaneous 50 eV acetylene ion bombardment. Surface chemistry of these nanocomposite films was first examined using stan ... [J. Vac. Sci. Technol. A 30, 04D109 (2012)] published Tue May 1, 2012.

Electrochemical Capacitances of a Nanowire-Structured MnO in Polyacrylate-Based Gel Electrolytes

Ho-Seong Nam, Nae-Lih Wu, Kuang-Tsin Lee, Kwang Man Kim, Chul Gi Yeom et al.
Nanowire-structured MnO was synthesized by a sonochemical method and its electrochemical capacitances were investigated in three kinds of electrolytes: liquid-type KCl solution, potassium polyacrylate (PAAK), and potassium polyacrylate-co-polyacrylamide (PAAK-PAAM) gel polymer electrolytes (GPEs). T ... [J. Electrochem. Soc. 159, A899 (2012)] published Mon Apr 30, 2012.

Time evolution of the structure of organoclay/polypropylene nanocomposites and application of the time-temperature superposition principle

R. Zouari, T. Domenech, B. Vergnes, and E. Peuvrel-Disdier
We investigated the rheological properties of nanocomposites composed of polypropylene, organoclay, and maleic anhydride grafted polypropylene in small amplitude oscillatory shear. Samples were prepared in two steps: a masterbatch was first obtained by melt extrusion and then diluted into polypropyl ... [J. Rheol. 56, 725 (2012)] published Thu May 3, 2012.

Surface-induced phase behavior of polymer/nanoparticle blends with attractions

Amalie L. Frischknecht, Venkat Padmanabhan, and Michael E. Mackay
In an athermal blend of nanoparticles and homopolymer near a hard wall, there is a first order phase transition in which the nanoparticles segregate to the wall and form a densely packed monolayer above a certain nanoparticle density. Previous investigations of this phase transition employed a fluid ... [J. Chem. Phys. 136, 164904 (2012)] published Fri Apr 27, 2012.

Nanosponges for hydrogen storage

Maurice Schlichtenmayer and Michael Hirscher
Hydrogen storage by physisorption is a very promising technique due to its fast kinetics and full reversibility. The key to reach high storage capacities is high specific surface area. Extremely large surface areas can only be achieved by materials with high porosity, i.e., nanosponges like MOF-177 ... [J. Mater. Chem. 22, 10134 (2012)] published Thu May 3, 2012.

Poly(3-hydroxyalkanoate)-derived amphiphilic graft copolymers for the design of polymersomes

Julien Babinot, Jean-Michel Guigner, Estelle Renard, and Valerie Langlois
Amphiphilic graft copolymers composed of biocompatible bacterial poly(3-hydroxyalkanoate) and poly(ethylene glycol) have been synthesized by thiolene addition. They were demonstrated to form well-defined nanoscale vesicles in water by cryo-transmission electron microscopy. ... [Chem. Commun. 48, 5364 (2012)] published Thu May 3, 2012.

Highly biocompatible, hollow coordination polymer nanoparticles as cisplatin carriers for efficient intracellular drug delivery

Hong-Yuan Lian, Ming Hu, Chia-Hung Liu, Yusuke Yamauchi, and Kevin C.-W. Wu
Highly biocompatible coordination polymer (Prussian Blue) nanoparticles (LC > 1000 [mu]g mL) with a hollow interior and a microporous framework (denoted as HPB) are utilized as an anticancer drug (i.e. cisplatin) capsule for chemotherapy of bladder cancer T24 cells. ... [Chem. Commun. 48, 5151 (2012)] published Thu May 3, 2012.

Pseudorotaxanes from self-assembly of two crown ether-based cryptands and a 1,2-bis(pyridinium) ethane derivative

Xuzhou Yan, Peifa Wei, Binyuan Xia, Feihe Huang, and Qizhong Zhou
Pseudorotaxanes from self-assembly of two crown ether-based cryptand wheels and a 1,2-bis(pyridinium) ethane derivative axle were prepared. ... [Chem. Commun. 48, 4968 (2012)] published Thu May 3, 2012.

Electronic structures of one-dimensional metalmolecule hybrid chains studied using scanning tunneling microscopy and density functional theory

Kyung-Hoon Chung, Bon-Gil Koo, Howon Kim, Jong Keon Yoon, Ji-Hoon Kim et al.
The electronic structures of self-assembled hybrid chains comprising Ag atoms and organic molecules were studied using scanning tunneling microscopy (STM) and spectroscopy (STS) in parallel with density functional theory (DFT). Hybrid chains were prepared by catalytic breaking of BrC bonds in 4,4[do ... [Phys. Chem. Chem. Phys. 14, 7304 (2012)] published Thu May 3, 2012.

Waveguide terahertz time-domain spectroscopy of ammonium nitrate polycrystalline films

Ani Khachatrian, Joseph S. Melinger, and Syed B. Qadri
We report temperature-dependent measurements of the terahertz (THz) vibrational spectrum of ammonium nitrate (AN) films and mixed potassium nitrate (KN)ammonium nitrate films using waveguide THz time domain spectroscopy. The experiments were performed on polycrystalline films on the metal surface of ... [J. Appl. Phys. 111, 093103 (2012)] published Thu May 3, 2012.

Programmable self-assembly of homo- or hetero-metallomacrocycles using 4-(1H-pyrazolyl-4-yl)pyridine

Jin Tong, Shu-Yan Yu, and Hui Li
The dimetallic [M(bpy)(NO)](NO) moieties (M = Pd(ii) or Pt(ii)) react preferentially at the pyrazolyl end of the pyridyl-pyrazole ligand, giving rise to dimetallic corners. Subsequently, the dimetallic corner building blocks featuring two pyridine donors are coordinated by monometallic [M(bpy)(NO)] ... [Chem. Commun. 48, 5343 (2012)] published Thu May 3, 2012.

Tetraferrocenylporphyrins as active components of self-assembled monolayers on gold surface

Andrea Vecchi, Emanuela Gatto, Barbara Floris, Valeria Conte, Mariano Venanzi et al.
Novel tetraferrocenylporphyrins-containing self-assembled monolayers were prepared employing two different approaches. Self-assembled monolayers were characterized using UV-Vis spectroscopy and cyclic voltammetry (CV) whereas their photoelectrochemical properties were investigated by photocurrent ge ... [Chem. Commun. 48, 5145 (2012)] published Thu May 3, 2012.

The formation and magnetism of iron nanostructures on ordered polymer templates

K Schlage, S Couet, S Roth, U Vainio, R Rffer et al.
We have followed the self-assembly of a magnetic antidot array during Fe sputter deposition onto a highly ordered, nanostructured polymer template by using a new kind of synchrotron radiation three-dimensional x-ray microscopy. The structural growth, chemical state (the formation of oxides) and the ... [New J. Phys. 14, 043007 (2012)] published Wed May 2, 2012.

Liquid-crystal-mediated self-assembly at nanodroplet interfaces

J. A. Moreno-Razo, E. J. Sambriski, N. L. Abbott, J. P. Hernndez-Ortiz, and J. J. de Pablo
Technological applications of liquid crystals have generally relied on control of molecular orientation at a surface or an interface. Such control has been achieved through topography, chemistry and the adsorption of monolayers or surfactants. The role of the substrate or interface has been to impa ... [Nature 485, 86 (2012)] published Thu May 3, 2012.

Crystal morphology-directed framework orientation in porous coordination polymer films and freestanding membranes via LangmuirBlodgettry

Manuel Tsotsalas, Ayako Umemura, Franklin Kim, Yoko Sakata, Julien Reboul et al.
Porous coordination polymers (PCPs), with their ordered nanoporous systems and large surface areas, are very attractive for numerous applications that involve controlled molecular transport properties. To fully exploit their potential, a straightforward processing method to deposit the PCP crystals ... [J. Mater. Chem. 22, 10159 (2012)] published Thu May 3, 2012.

Light emission and spin-polarised hole injection in InAs/GaAs quantum dot heterostructures with Schottky contact

N. Baidus, M. Vasilevskiy, S. Khazanova, B. Zvonkov, H. van der Meulen et al.
We demonstrate the feasibility to obtain electroluminescence (EL), up to room temperature, from InGaAs self-assembled quantum dots (QDs) included in a forward-biased Schottky diode. Moreover, using a ferromagnet (FM) as the contact layer, sizable circular polarization of the EL emission in the prese ... [EPL 98, 27012 (2012)] published Wed May 2, 2012.

New monoacylhydrazidate-coordinated Mn and Pb compounds

Juan Jin, Fu-Quan Bai, Ming-Jun Jia, Jie-Hui Yu, and Ji-Qing Xu
By the simple hydrothermal self-assembly, four new monoacylhydrazidate-coordinated compounds [Mn(APTH)(HO)] 1, [Pb(APTH)]0.25HO 2, [Pb(EPDH)(HO)] 3 and [Pb(MPDH)] 4 (APTH = 3-aminophthalhydrazidate, EPDH = 5-ethylpyridine-2,3-dicarboxylhydrazidate, MPDH = 6-methylpyrinde-2,3-dicarboxylhydrazidate) w ... [Dalton Trans. 41, 6137 (2012)] published Thu May 3, 2012.

Unique nanoscale {Cu Ln } (Ln = Dy and Gd) metallo-rings

Ji-Dong Leng, Jun-Liang Liu, and Ming-Liang Tong
Two unprecedented 3d4f hexagonal metallo-rings {LnCu} (Ln = Dy and Gd) with a diagonal dimension of about 4.6 nm were facilely synthesized by self-assembly of Cu, Ln nitrates and benzoate in the presence of triethylamine. Magnetic studies show slow relaxation behaviour for the dysprosium analogue an ... [Chem. Commun. 48, 5286 (2012)] published Thu May 3, 2012.

Metal-mediated self-assembly of tetrapyridyl porphyrins by Na ions

Mariachiara Trapani, Maria Rosaria Plutino, Giuseppe Sabatino, Ilaria Occhiuto, Anna Borriello et al.
In the presence of the sodium salt of a bulky anion, which allows the solubility of Na in low polarity solvents, various tetra(4-pyridyl)porphyrin derivatives can spontaneously self-assemble from CHCl into supramolecular nanostructures exhibiting a long-range order, through the coordination of Na io ... [Chem. Commun. 48, 5136 (2012)] published Thu May 3, 2012.

Modular self-assembled multiporphyrin cages with tunable shape

Enzo Alessio, Massimo Casanova, Ennio Zangrando, and Elisabetta Iengo
Three new molecular cagesa trigonal prism (2) and two cubic-shaped boxes of increasing size (3, 4)featuring as many as 10 porphyrins were obtained in quantitative yields by self-assembly of a single bis-zincporphyrin metallacycle (1) with appropriate polytopic N-linkers: the trigonal planar tpt or t ... [Chem. Commun. 48, 5112 (2012)] published Thu May 3, 2012.

Tailoring ordered taper-nanopore arrays by combined nanosphere self-assembling, imprinting, anodizing and etching

Congshan Li, Juan Li, Cheng Chen, Jie Zhu, and Xuefeng Gao
We report a simple and effective method for tailoring ordered three-dimensional alumina taper-nanopore arrays, dispensing with any unavailable and expensive top-down equipment. ... [Chem. Commun. 48, 5100 (2012)] published Thu May 3, 2012.

A novel method for preparing silver nanoparticlehydrogel nanocomposites via pH-induced self-assembly

Ju Young Yook, Gwang-Ho Choi, and Dong Hack Suh
We present a novel and facile method to fabricate the silver nanoparticle (AgNP)sodium deoxycholate (NaDOC) hybrid hydrogel from the NaDOC-stablized AgNP colloidal hydrosol via the pH-induced self-assembly. ... [Chem. Commun. 48, 5001 (2012)] published Thu May 3, 2012.

Intrinsic disorder modulates protein self-assembly and aggregation

Alfonso De Simone, Craig Kitchen, Ann H. Kwan, Margaret Sunde, Christopher M. Dobson et al.
Protein molecules have evolved to adopt distinctive and well-defined functional and soluble states under physiological conditions. In some circumstances, however, proteins can self-assemble into fibrillar aggregates designated as amyloid fibrils. In vivo these processes are normally associated with ... [Proc. Natl. Acad. Sci. U.S.A. 109, 6951 (2012)] published Wed May 2, 2012.

A vapoluminescent Eu-based metallo-supramolecular polymer

Takashi Sato and Masayoshi Higuchi
An Eu-based metallo-supramolecular polymer (polyEu) was prepared by self-assembly coordination polymerization. Unique vapoluminescence property of polyEu triggered by acidbase vapor was found and a photoluminescence display in switchable imaging by acidbase vapor was fabricated. ... [Chem. Commun. 48, 4947 (2012)] published Thu May 3, 2012.

Perfect sampling with unitary tensor networks

Andrew J. Ferris and Guifre Vidal
Tensor network states are powerful variational Ansatze for many-body ground states of quantum lattice models. The use of Monte Carlo sampling techniques in tensor network approaches significantly reduces the cost of tensor contractions, potentially leading to a substantial increase in computational ... [Phys. Rev. B 85, 165146 ] published .

General quantum-state swap: An XY-model analysis

Ben-Qiong Liu, Lian-Ao Wu, Bin Shao, and Jian Zou
We consider an exact state swap, defined as the swap between two quantum states |A> and |B> in the Hilbert space of a quantum system. We show that given an arbitrary Hamiltonian dynamics, there is a straightforward approach to calculating the probability of the occurrence of an exact state swap by e ... [Phys. Rev. A 85, 042328 ] published .

Towards Practical Classical Processing for the Surface Code

Austin G. Fowler, Adam C. Whiteside, and Lloyd C. L. Hollenberg
The surface code is unarguably the leading quantum error correction code for 2D nearest neighbor architectures, featuring a high threshold error rate of approximately 1%, low overhead implementations of the entire Clifford group, and flexible, arbitrarily long-range logical gates. These highly desir ... [Phys. Rev. Lett. 108, 180501 ] published .

Driven Dynamics and Rotary Echo of a Qubit Tunably Coupled to a Harmonic Oscillator

S. Gustavsson, J. Bylander, F. Yan, P. Forn-Diaz, V. Bolkhovsky et al.
We have investigated the driven dynamics of a superconducting flux qubit that is tunably coupled to a microwave resonator. We find that the qubit experiences an oscillating field mediated by off-resonant driving of the resonator, leading to strong modifications of the qubit Rabi frequency. This open ... [Phys. Rev. Lett. 108, 170503 ] published .

Variational Monte Carlo with the multiscale entanglement renormalization ansatz

Andrew J. Ferris and Guifre Vidal
Monte Carlo sampling techniques have been proposed as a strategy to reduce the computational cost of contractions in tensor network approaches to solving many-body systems. Here, we put forward a variational Monte Carlo approach for the multiscale entanglement renormalization ansatz (MERA), which is ... [Phys. Rev. B 85, 165147 ] published .

Classification of General n-Qubit States under Stochastic Local Operations and Classical Communication in Terms of the Rank of Coefficient Matrix

Xiangrong Li and Dafa Li
We solve the entanglement classification under stochastic local operations and classical communication (SLOCC) for general n-qubit states. For two arbitrary pure n-qubit states connected via local operations, we establish an equation between the two coefficient matrices associated with the states. T ... [Phys. Rev. Lett. 108, 180502 ] published .

Complete entanglement witness for quantum teleportation

Ming-Jing Zhao, Shao-Ming Fei, and Xianqing Li-Jost
We propose a set of linear quantum entanglement witnesses constituted by local quantum-mechanical observables with each two possible measurement outcomes. These witnesses detect all the entangled resources which give rise to a better fidelity than separable states in quantum teleportation and presen ... [Phys. Rev. A 85, 054301 ] published .

Coherent optimal control of photosynthetic molecules

F. Caruso, S. Montangero, T. Calarco, S. F. Huelga, and M. B. Plenio
We demonstrate theoretically that open-loop quantum optimal control techniques can provide efficient tools for the verification of various quantum coherent transport mechanisms in natural and artificial light-harvesting complexes under realistic experimental conditions. To assess the feasibility of ... [Phys. Rev. A 85, 042331 ] published .

Symmetry and localization of quantum walks induced by an extra link in cycles

Xin-Ping Xu, Yusuke Ide, and Norio Konno
It is generally believed that network structure has a profound impact on diverse dynamical processes taking place on networks. Tiny changes in the structure may cause completely different dynamics. In this paper, we study the impact of single extra link on the coherent dynamics modeled by continuous ... [Phys. Rev. A 85, 042327 ] published .

Electrically driven single-photon source at room temperature in diamond

N. Mizuochi, T. Makino, H. Kato, D. Takeuchi, M. Ogura et al.
Single-photon sources that provide non-classical light states on demand have a broad range of applications in quantum communication, quantum computing and metrology. Single-photon emission has been demonstrated using single atoms, ions, molecules, diamond colour centres and semiconductor quantum dot ... [Nat. Photonics 6, 299 (2012)] published Wed May 2, 2012.

Electric field tuning of spin splitting in a quantum dot coupled to a semimagnetic quantum dot

Y. Lyanda-Geller, T. L. Reinecke, and G. Bacher
We develop an approach for tuning the spin splitting and g-factor of a quantum dot by coupling it to semi-magnetic quantum dot and tuning the electric field. We show that spin splittings and g-factors of the states of a non-magnetic quantum dot coupled to semimagnetic quantum dot can be enhanced ord ... [J. Appl. Phys. 111, 093705 (2012)] published Thu May 3, 2012.

Transmission of electron through monolayer graphene laser barrier

C. Sinha and R. Biswas
The present theoretical model deals with the transmission property of the Dirac fermions in the Floquet sidebands for the laser radiated graphene nanostructure. The laser assisted structure behaves as a tunneling barrier that leads to asymmetric transmission around the normal to the interface and is ... [Appl. Phys. Lett. 100, 183107 (2012)] published Thu May 3, 2012.

Designing biomimetic pores based on carbon nanotubes

Rebeca Garcia-Fandino and Mark S. P. Sansom
Biomimetic nanopores based on membrane-spanning single-walled carbon nanotubes have been designed to include selectivity filters based on combinations of anionic and cationic groups mimicking those present in bacterial porins and in voltage-gated sodium and calcium channels. The ion permeation and ... [Proc. Natl. Acad. Sci. U.S.A. 109, 6939 (2012)] published Wed May 2, 2012.

Distinguishing Spontaneous Quantum Hall States in Bilayer Graphene

Fan Zhang and A. H. MacDonald
Chirally stacked N-layer graphene with N>=2 is susceptible to a variety of distinct broken symmetry states in which each spin-valley flavor spontaneously transfers charge between layers. In mean-field theory, one of the likely candidate ground states for a neutral bilayer is the layer antiferromagne ... [Phys. Rev. Lett. 108, 186804 ] published .

Acoustic Analogue of Graphene: Observation of Dirac Cones in Acoustic Surface Waves

Daniel Torrent and Jose Sanchez-Dehesa
We demonstrate the presence of Dirac cones in the dispersion relation of acoustic waves propagating on the surface of a plate of methyl methacrylate containing a honeycomb lattice of cylindrical boreholes. This structure represents the acoustic analogue of graphene, the cylindrical cavities playing ... [Phys. Rev. Lett. 108, 174301 ] published .

Zero-bias conductance peak and Josephson effect in graphene-NbTiN junctions

M. Popinciuc, V. E. Calado, X. L. Liu, A. R. Akhmerov, T. M. Klapwijk et al.
We report electronic transport measurements of graphene contacted by NbTiN electrodes, which at low temperature remain superconducting up to at least 11 T. In devices with a single superconducting contact, we find a more than twofold enhancement of the conductance at zero bias, which we interpret in ... [Phys. Rev. B 85, 205404 ] published .

Theoretical study of the charge transport through C-based single-molecule junctions

S. Bilan, L. A. Zotti, F. Pauly, and J. C. Cuevas
We present a theoretical study of the conductance and thermopower of single-molecule junctions based on C and C-terminated molecules. We first analyze the transport properties of gold-C-gold junctions and show that these junctions can be highly conductive (with conductances above 0.1G, where G=2e/h ... [Phys. Rev. B 85, 205403 ] published .

Ab initio studies of hydrogen adatoms on bilayer graphene

R. E. Mapasha, A. M. Ukpong, and N. Chetty
We present a comparative density functional study of the adsorption of hydrogen on bilayer graphene. Six different exchange-correlation functionals are employed to explore the possible configurations of hydrogen adsorption at 50% coverage. Using the four variants of the nonlocal van der Waals densit ... [Phys. Rev. B 85, 205402 ] published .

Coherent radial-breathing-like phonons in graphene nanoribbons

G. D. Sanders, A. R. T. Nugraha, R. Saito, and C. J. Stanton
We have developed a microscopic theory for the generation and detection of coherent phonons in armchair and zigzag graphene nanoribbons using an extended tight-binding model for the electronic states and a valence force field model for the phonons. The coherent phonon amplitudes satisfy a driven osc ... [Phys. Rev. B 85, 205401 ] published .

Graphene under spatially varying external potentials: Landau levels, magnetotransport, and topological modes

Si Wu, Matthew Killi, and Arun Paramekanti
Superlattices (SLs) in monolayer and bilayer graphene, formed by spatially periodic potential variations, lead to a modified bandstructure with extra finite-energy and zero-energy Dirac fermions with tunable anisotropic velocities. We theoretically show that transport in a weak perpendicular (orbita ... [Phys. Rev. B 85, 195404 ] published .

Quantum interference corrections to magnetoconductivity in graphene

S. Pezzini, C. Cobaleda, E. Diez, and V. Bellani
We studied weak localization (WL) and antilocalization (WAL) in graphene at temperatures between 0.3 K and 15 K. At low carrier density, we observed a transition from WL to WAL driven by the increasing of the magnetic field while at high carrier density, WAL was suppressed as a consequence of trigon ... [Phys. Rev. B 85, 165451 ] published .

Silicon intercalation into the graphene-SiC interface

F. Wang, K. Shepperd, J. Hicks, M. S. Nevius, H. Tinkey et al.
In this work we use low-energy electron microscopy, x-ray photoemission electron microscopy, and x-ray photoelectron spectroscopy to study how the excess Si at the graphene-vacuum interface reorders itself at high temperatures. We show that silicon deposited at room temperature onto multilayer graph ... [Phys. Rev. B 85, 165449 ] published .

Tunable quantum dots in monolayer graphene

G. Giavaras and Franco Nori
We examine a graphene quantum dot formed by combining an electric and a uniform magnetic field. The electric field creates a smooth quantum well potential while the magnetic field induces an exponential tail to the dot states. The states peak in the well and the electrostatic barrier region as a res ... [Phys. Rev. B 85, 165446 ] published .

Nonlinear resistivity and heat dissipation in monolayer graphene

A. S. Price, S. M. Hornett, A. V. Shytov, E. Hendry, and D. W. Horsell
We have experimentally studied the nonlinear nature of electrical conduction in monolayer graphene devices on silica substrates. This nonlinearity manifests itself as a nonmonotonic dependence of the differential resistance on applied dc voltage bias across the sample. At temperatures below ~70 K, t ... [Phys. Rev. B 85, 161411 ] published .

Absence of dynamical gap generation in suspended graphene

Jing-Rong Wang and Guo-Zhu Liu
There is an interesting proposal that the long-range Coulomb interaction in suspended graphene can generate a dynamical gap, which leads to a semimetalinsulator phase transition. We revisit this problem by solving the self-consistent DysonSchwinger equations of wave function renormalization and ferm ... [New J. Phys. 14, 043036 (2012)] published Wed May 2, 2012.

Modification in electrical transport with a change in geometry from a nanowire to a nanotube of copper: effect of the extra surface

M Venkata Kamalakar and A Raychaudhuri
We have studied the temperature-dependent (3300K) electrical resistance of metal nanowires and nanotubes of the same diameter with the specific aim to understand the changes in electrical transport brought about by a change in the geometry of a nanowire to a nanotube. Single crystalline nanowires an ... [New J. Phys. 14, 043032 (2012)] published Wed May 2, 2012.

Exceptional high Seebeck coefficient and gas-flow-induced voltage in multilayer graphene

Xuemei Li, Jun Yin, Jianxin Zhou, Qin Wang, and Wanlin Guo
Seebeck coefficient of graphene is an important parameter for defining its thermoelectric performance and thus practical applications, such as gas-flow-induced voltage. Here, we find a unique layer-dependence of the graphene Seebeck coefficient that exceptionally increases with increasing thickness ... [Appl. Phys. Lett. 100, 183108 (2012)] published Thu May 3, 2012.

Nonlinear graphene metamaterial

Andrey E. Nikolaenko, Nikitas Papasimakis, Evangelos Atmatzakis, Zhiqiang Luo, Ze Xiang Shen et al.
We demonstrate that the broadband nonlinear optical response of graphene can be resonantly enhanced by more than an order of magnitude through hybridization with a plasmonic metamaterial, while retaining an ultrafast nonlinear response time of ~1 ps. Transmission modulation close to ~1% is seen at a ... [Appl. Phys. Lett. 100, 181109 (2012)] published Thu May 3, 2012.

N-channel carbon nanotube enabled vertical field effect transistors with solution deposited ZnO nanoparticle based channel layers

Po-Hsiang Wang, Bo Liu, Yu Shen, Ying Zheng, Mitchell A. McCarthy et al.
N-channel carbon nanotube enabled vertical field effect transistors (CN-VFETs) exploiting a solution deposited ZnO nanoparticle thin film as the channel material are demonstrated. Transistor performance benefits from a thermal anneal followed by an oxygen plasma treatment. The devices exhibit on/off ... [Appl. Phys. Lett. 100, 173514 (2012)] published Fri Apr 27, 2012.

Orbital magnetic susceptibility of finite-sized graphene

Yuya Ominato and Mikito Koshino
We study the orbital magnetism of graphene ribbon in the effective-mass approximation, to figure out the finite-size effect on the singular susceptibility known in the bulk limit. We find that the susceptibility at T=0 oscillates between diamagnetism and paramagnetism as a function of [eh], in accor ... [Phys. Rev. B 85, 165454 ] published .

Emergence of superlattice Dirac points in graphene on hexagonal boron nitride

Matthew Yankowitz, Jiamin Xue, Daniel Cormode, Javier D. Sanchez-Yamagishi, K. Watanabe et al.
The Schrdinger equation dictates that the propagation of nearly free electrons through a weak periodic potential results in the opening of bandgaps near points of the reciprocal lattice known as Brillouin zone boundaries. However, in the case of massless Dirac fermions, it has been predicted that t ... [Nature Phys. 8, 382 (2012)] published Wed May 2, 2012.

Effect of charge-transfer complex on the energy level alignment between graphene and organic molecules

Giyeol Bae, Hyun Jung, Noejung Park, Jinwoo Park, Suklyun Hong et al.
We performed density-functional theory calculations to study the electronic structures at the interfaces between graphene and organic molecules that have been used in organic light-emitting diodes. In terms of work function, graphene itself is not favorable as either anode or cathode for commonly us ... [Appl. Phys. Lett. 100, 183102 (2012)] published Tue May 1, 2012.

How does water-nanotube interaction influence water flow through the nanochannel?

Xiaoyi Li, Yanchao Shi, Yuling Yang, Huailiang Du, Ruhong Zhou et al.
Water permeation across various nitrogen-doped double-walled carbon nanotubes (N-DWCNT) has been studied with molecular dynamics simulations to better understand the influence of water-nanopore interaction on the water permeation rate. There exists a threshold interaction energy at around 34.1 kJ/mo ... [J. Chem. Phys. 136, 175101 (2012)] published Tue May 1, 2012.

Erythrocyte deformation in high-throughput optical stretchers

Ihab Sraj, Alex C. Szatmary, Sanjay A. Desai, David W. M. Marr, and Charles D. Eggleton
Optical stretchers can be used to quantify elastic and homeostatic properties of cells. Because they can apply forces to cells without requiring direct contact, they may noninvasively measure mechanical properties related to cell and membrane health. Present-day optical stretchers are, however, limi ... [Phys. Rev. E 85, 041923 ] published .

Synthetic routes toward MOF nanomorphologies

Erik A. Flugel, Annekathrin Ranft, Frederik Haase, and Bettina V. Lotsch
As metalorganic frameworks (MOFs) are coming of age, their structural diversity, exceptional porosity and inherent functionality need to be transferred into useful applications. Fashioning MOFs into various shapes and at the same time controlling their size constitute an essential step toward MOF-ba ... [J. Mater. Chem. 22, 10119 (2012)] published Thu May 3, 2012.

Microfluidic approach to genotyping human platelet antigens

C. Lim, D.P. Manage, A. Atrazhev, G. Denomme, C.J. Backhouse et al.
Centralised laboratories routinely determine blood types by serological and molecular methods. Current practices have limitations in terms of cost, time and accessibility. Miniaturised microfluidic platforms offer an alternative to conventional genotyping methods, since they consume fewer reagents, ... [IET Nanobiotechnol. 6, 33 (2012)] published Thu May 3, 2012.

Electronic detection of dielectrophoretic forces exerted on particles flowing over interdigitated electrodes

Marija Nikolic-Jaric, Sean F. Romanuik, Graham A. Ferrier, Tim Cabel, Elham Salimi et al.
Dielectric particles flowing through a microfluidic channel over a set of coplanar electrodes can be simultaneously capacitively detected and dielectrophoretically (DEP) actuated when the high (1.45 GHz) and low (100 kHz20 MHz) frequency electromagnetic fields are concurrently applied through the sa ... [Biomicrofluidics 6, 024117 (2012)] published Thu May 3, 2012.

Manipulating single annealed polyelectrolyte under alternating current electric fields: Collapse versus accumulation

Shengqin Wang and Yingxi Zhu
Effective manipulation and understanding of the structural and dynamic behaviors of a single polyelectrolyte (PE) under alternating current (AC) electric fields are of great scientific and technological importance because of its intimate relevance to emerging bionanotechnology. In this work, we empl ... [Biomicrofluidics 6, 024116 (2012)] published Tue May 1, 2012.

Ultrahigh-Q mechanical oscillators through optical trapping

D Chang, K-K Ni, O Painter, and H Kimble
Rapid advances are being made toward optically cooling a single mode of a micro-mechanical system to its quantum ground state and observing the quantum behavior at macroscopic scales. Reaching this regime in room-temperature environments requires a stringent condition on the mechanical quality facto ... [New J. Phys. 14, 045002 (2012)] published Wed May 2, 2012.

Frequency and phase noise of ultrahigh Q silicon nitride nanomechanical resonators

King Y. Fong, Wolfram H. P. Pernice, and Hong X. Tang
We describe the measurement and modeling of amplitude noise and phase noise in ultrahigh Q nanomechanical resonators made from stoichiometric silicon nitride. With quality factors exceeding 2 million, the resonators' noise performance is studied with high precision. We find that the amplitude noise ... [Phys. Rev. B 85, 161410 ] published .

High-Q silicon optomechanical microdisk resonators at gigahertz frequencies

Xiankai Sun, Xufeng Zhang, and Hong X. Tang
We report disk-shaped silicon optomechanical resonators with frequency up to 1.75 GHz in the ultrahigh frequency band. Optical transduction of the thermal motion of the disks' in-plane vibrational modes yields a displacement sensitivity of 4.1 x 10 m/Hz. Due to the reduced clamping loss, these dis ... [Appl. Phys. Lett. 100, 173116 (2012)] published Fri Apr 27, 2012.

Phonon-cavity electromechanics

I. Mahboob, K. Nishiguchi, H. Okamoto, and H. Yamaguchi
Photonic cavities have emerged as an indispensable tool to control and manipulate harmonic motion in opto/electromechanical systems. Invariably, in these systems a high-quality-factor photonic mode is parametrically coupled to a high-quality-factor mechanical oscillation mode. This entails the dema ... [Nature Phys. 8, 387 (2012)] published Wed May 2, 2012.

Cascaded plasmon resonant field enhancement in nanoparticle dimers in the point dipole limit

Seyfollah Toroghi and Pieter G. Kik
Cascaded field enhancement in silver dimer nanostructures is investigated using a dipole-dipole interaction model. Field enhancement spectra are evaluated as a function of the particle size difference and inter-particle spacing. We observe three distinct regimes of cascaded field enhancement: hinder ... [Appl. Phys. Lett. 100, 183105 (2012)] published Wed May 2, 2012.

Partially disordered photonic-crystal thin films for enhanced and robust photovoltaics

Ardavan Oskooi, Pedro A. Favuzzi, Yoshinori Tanaka, Hiroaki Shigeta, Yoichi Kawakami et al.
We present a general framework for the design of thin-film photovoltaics based on a partially disordered photonic crystal that has both enhanced absorption for light trapping and reduced sensitivity to the angle and polarization of incident radiation. The absorption characteristics of different latt ... [Appl. Phys. Lett. 100, 181110 (2012)] published Thu May 3, 2012.

Enhancement in light emission efficiency of Si nanocrystal light-emitting diodes by a surface plasmon coupling

Chul Huh, Chel-Jong Choi, Wanjoong Kim, Bong Kyu Kim, Byoung-Jun Park et al.
We report an enhancement in light emission efficiency form Si nanocrystal (NC) light-emitting diodes (LEDs) via surface plasmons (SPs) by employing Au nanoparticles (NPs). Photoluminescence intensity of Si NCs with Au NPs was enhanced by 2 factors of magnitude due to the strong coupling of Si NCs an ... [Appl. Phys. Lett. 100, 181108 (2012)] published Wed May 2, 2012.

Excitation energy dependence of the exciton inner ring

Y. Y. Kuznetsova, J. R. Leonard, L. V. Butov, J. Wilkes, E. A. Muljarov et al.
We report on the excitation energy dependence of the inner ring in the exciton emission pattern. The contrast of the inner ring is found to decrease with lowering excitation energy. Excitation by light tuned to the direct exciton resonance is found to effectively suppress excitation-induced heating ... [Phys. Rev. B 85, 165452 ] published .

Phonon-mediated coupling between quantum dots through an off-resonant microcavity

Arka Majumdar, Michal Bajcsy, Armand Rundquist, Erik Kim, and Jelena VuCkovic
We present experimental results showing phonon-mediated coupling between two quantum dots embedded inside a photonic-crystal microcavity. With only one of the dots being spectrally close to the cavity, we observe both frequency up-conversion and down-conversion of the pump light via a ~1.2-THz phono ... [Phys. Rev. B 85, 195301 ] published .

Transformation optics description of touching metal nanospheres

A. I. Fernandez-Dominguez, S. A. Maier, and J. B. Pendry
We present an insightful theoretical description of the optical properties of touching metal nanospheres. Our approach, which exploits transformation optics ideas within the quasistatic approximation, yields simple expressions for all the relevant electromagnetic magnitudes in these singular nanopar ... [Phys. Rev. B 85, 165148 ] published .

Persistent Narrowing of Nuclear-Spin Fluctuations in InAs Quantum Dots Using Laser Excitation

Bo Sun, Colin Ming Earn Chow, Duncan G. Steel, Allan S. Bracker, Daniel Gammon et al.
We demonstrate the suppression of nuclear-spin fluctuations in an InAs quantum dot and measure the timescales of the spin narrowing effect. By initializing for tens of milliseconds with two continuous wave diode lasers, fluctuations of the nuclear spins are suppressed via the hole-assisted dynamic n ... [Phys. Rev. Lett. 108, 187401 ] published .

Intrinsic Spin Fluctuations Reveal the Dynamical Response Function of Holes Coupled to Nuclear Spin Baths in (In,Ga)As Quantum Dots

Yan Li, N. Sinitsyn, D. L. Smith, D. Reuter, A. D. Wieck et al.
The problem of how single central spins interact with a nuclear spin bath is essential for understanding decoherence and relaxation in many quantum systems, yet is highly nontrivial owing to the many-body couplings involved. Different models yield widely varying time scales and dynamical responses ( ... [Phys. Rev. Lett. 108, 186603 ] published .

Loss-Enabled Sub-Poissonian Light Generation in a Bimodal Nanocavity

Arka Majumdar, Michal Bajcsy, Armand Rundquist, and Jelena VuCkovic
We propose an implementation of a source of strongly sub-Poissonian light in a system consisting of a quantum dot coupled to both modes of a lossy bimodal optical cavity. When one mode of the cavity is resonantly driven with coherent light, the system will act as an efficient single photon filter, a ... [Phys. Rev. Lett. 108, 183601 ] published .

Direct generation of multiple excitons in adjacent silicon nanocrystals revealed by induced absorption

M. Tuan Trinh, Rens Limpens, Wieteke D. A. M. de Boer, Juleon M. Schins, Laurens D. A. Siebbeles et al.
The enhancement of carrier multiplication in semiconductor nanocrystals attracts a great deal of attention because of its potential in photovoltaic applications. Here, we present the results of investigations of a novel carrier multiplication mechanism recently proposed for closely spaced silicon na ... [Nat. Photonics 6, 316 (2012)] published Wed May 2, 2012.

Unified picture of cantilever frequency shift measurements of magnetic resonance

SangGap Lee, Eric W. Moore, and John A. Marohn
We report a unified framework describing all existing protocols for spin manipulation and signal creation in frequency-modulation magnetic resonance force microscopy using classical perturbation theory. The framework is well suited for studying the dependence of the frequency shift on the cantilever ... [Phys. Rev. B 85, 165447 ] published .

Controlling waves in space and time for imaging and focusing in complex media

Allard P. Mosk, Ad Lagendijk, Geoffroy Lerosey, and Mathias Fink
In complex media such as white paint and biological tissue, light encounters nanoscale refractive-index inhomogeneities that cause multiple scattering. Such scattering is usually seen as an impediment to focusing and imaging. However, scientists have recently used strongly scattering materials to fo ... [Nat. Photonics 6, 283 (2012)] published Wed May 2, 2012.

Resonant microwave-to-spin-wave transducer

Y. Au, E. Ahmad, O. Dmytriiev, M. Dvornik, T. Davison et al.
We use time resolved scanning Kerr microscopy and analytical and numerical calculations to demonstrate coupling of uniform global microwave field to propagating spin waves for emerging magnonic architectures. The coupling is mediated by the local dynamic dipolar field produced by the magnetization o ... [Appl. Phys. Lett. 100, 182404 (2012)] published Wed May 2, 2012.

Measurement and simulation of anisotropic magnetoresistance in single GaAs/MnAs core/shell nanowires

J. Liang, J. Wang, A. Paul, B. J. Cooley, D. W. Rench et al.
We report four probe measurements of the low field magnetoresistance (MR) in single core/shell GaAs/MnAs nanowires (NWs) synthesized by molecular beam epitaxy, demonstrating clear signatures of anisotropic magnetoresistance that track the field-dependent magnetization. A comparison with micromagneti ... [Appl. Phys. Lett. 100, 182402 (2012)] published Tue May 1, 2012.

Quantum depinning of the magnetic vortex core in micron-size permalloy disks

Ricardo Zarzuela, Saul Velez, Joan Manel Hernandez, Javier Tejada, and Valentyn Novosad
The vortex state, characterized by an in-plane closed flux domain structure and an out-of-plane magnetization at its center (the vortex core), is one of the magnetic equilibria of thin soft ferromagnetic micron-size dots. In the past two decades many groups have been working on the dynamics of the m ... [Phys. Rev. B 85, 180401 ] published .

Magnetic properties of ZnO nanoclusters

X. G. Zhao and Z. Tang
First-principles calculations were employed to study the magnetic properties of ZnO nanoclusters (NCs). It is demonstrated that the magnetism of the ZnO nanoclusters is dominated by the dangling-bond states of the surface oxygen ions surrounded by two Zn cations. Such surface-state driven magnetism ... [J. Appl. Phys. 111, 084321 (2012)] published Mon Apr 30, 2012.

Modulation of domain wall dynamics in TbFeCo single layer nanowire

Duc-The Ngo, Kotaro Ikeda, and Hiroyuki Awano
We demonstrate the possibility to write and modulate the magnetic domain walls in a TbFeCo single layer nanowire (300 nm width, 150 [mu]m length). To realize this, a tiny magnetic domain was nucleated by an Oersted field produced by a 1.6 MHz pulse current (35 mA in amplitude, 5-40 ns in length) cro ... [J. Appl. Phys. 111, 083921 (2012)] published Fri Apr 27, 2012.

Room-temperature ferromagnetism in epitaxial Mg-doped SnO thin films

Ping Wu, Baozeng Zhou, and Wei Zhou
The magnetic behavior of epitaxial Mg-doped SnO thin films prepared by radio-frequency magnetron sputtering was investigated in this work. Room-temperature ferromagnetism with the saturation magnetization of about 6.9 emu/cm was observed in 6% Mg-doped SnO samples. And the saturation magnetization d ... [Appl. Phys. Lett. 100, 182405 (2012)] published Thu May 3, 2012.

Spin-transfer switching in full-Heusler CoFeAl-based magnetic tunnel junctions

Hiroaki Sukegawa, Zhenchao Wen, Kouta Kondou, Shinya Kasai, Seiji Mitani et al.
We demonstrated spin-transfer magnetization switching using magnetic tunnel junctions (MTJs) with a full-Heusler alloy CoFeAl (CFA). We prepared CFA (1.5 nm)/MgO/CoFe (4 nm) (CFA-free) and CFA (30 nm)/MgO/CoFeB (2 nm) (CFA-reference) MTJs on a Cr(001) layer. The intrinsic critical current density (J ... [Appl. Phys. Lett. 100, 182403 (2012)] published Wed May 2, 2012.

Investigation of perpendicular magnetic anisotropy of CoFeB by x-ray magnetic circular dichroism

W. C. Tsai, S. C. Liao, H. C. Hou, C. T. Yen, Y. H. Wang et al.
We have studied the variation of perpendicular magnetic anisotropy (PMA) of CoFeB layers with the oxidation degree of the MgO buffer layers. After annealing at 330 degrees C, the out-of-plane anisotropy field (H) of 1.5-nm CoFeB could be optimized to 3.1 kOe. To investigate the orbital hybridizatio ... [Appl. Phys. Lett. 100, 172414 (2012)] published Fri Apr 27, 2012.

Spin-Orbital Short-Range Order on a Honeycomb-Based Lattice

S. Nakatsuji, K. Kuga, K. Kimura, R. Satake, N. Katayama et al.
Frustrated magnetic materials, in which local conditions for energy minimization are incompatible because of the lattice structure, can remain disordered to the lowest temperatures. Such is the case for Ba3CuSb2O9, which is magnetically anisotropic at the atomic scale but curiously isotropic on meso ... [Science 336, 559 (2012)] published Wed May 2, 2012.

Spin-Torque Switching with the Giant Spin Hall Effect of Tantalum

Luqiao Liu, Chi-Feng Pai, Y. Li, H. W. Tseng, D. C. Ralph et al.
Spin currents can apply useful torques in spintronic devices. The spin Hall effect has been proposed as a source of spin current, but its modest strength has limited its usefulness. We report a giant spin Hall effect (SHE) in -tantalum that generates spin currents intense enough to induce efficient ... [Science 336, 555 (2012)] published Wed May 2, 2012.

Thin-Film Magnetization Dynamics on the Surface of a Topological Insulator

Yaroslav Tserkovnyak and Daniel Loss
We theoretically study the magnetization dynamics of a thin ferromagnetic film exchange coupled with a surface of a strong three-dimensional topological insulator. We focus on the role of electronic zero modes imprinted by domain walls (DWs) or other topological textures in the magnetic film. Thermo ... [Phys. Rev. Lett. 108, 187201 ] published .

Gate-Controlled Spin Injection at LaAlO/SrTiO Interfaces

N. Reyren, M. Bibes, E. Lesne, J.-M. George, C. Deranlot et al.
We report results of electrical spin injection at the high-mobility quasi-two-dimensional electron system (2-DES) that forms at the LaAlO/SrTiO interface. In a nonlocal, three-terminal measurement geometry, we analyze the voltage variation associated with the precession of the injected spin accumula ... [Phys. Rev. Lett. 108, 186802 ] published .

Spin conduction in anisotropic three-dimensional topological insulators

Vincent E. Sacksteder, Stefan Kettemann, QuanSheng Wu, Xi Dai, and Zhong Fang
When topological insulators possess rotational symmetry their spin lifetime is tied to the scattering time. We show that in anisotropic topological insulators this tie can be broken and the spin lifetime can be very large. Two different mechanisms can obtain spin conduction over long distances. The ... [Phys. Rev. B 85, 205303 ] published .

Thermal switching rate of a ferromagnetic material with uniaxial anisotropy

Tomohiro Taniguchi and Hiroshi Imamura
The field dependence of the thermal switching rate of a ferromagnetic material with uniaxial anisotropy was studied by solving the Fokker-Planck equation. We derived the analytical expression of the thermal switching rate using the mean first-passage time approach and found that Brown's formula [Phy ... [Phys. Rev. B 85, 184403 ] published .

Photoinduced helical metal and magnetization in two-dimensional electron systems with spin-orbit coupling

Teemu Ojanen and Takuya Kitagawa
Helical metals realized at the surfaces of topological insulators have recently attracted wide attention due to their potential applications in spintronics. In this Rapid Communication we propose to realize helical metals through the application of THz light on common two-dimensional semiconductors ... [Phys. Rev. B 85, 161202 ] published .

Experimental observation of the optical spin transfer torque

P. Nmec, E. Rozkotov, N. Tesaov, F. Trojnek, E. De Ranieri et al.
The spin transfer torque is a phenomenon in which angular momentum of a spin polarized electrical current entering a ferromagnet is transferred to the magnetization. The effect has opened a new research field of electrically driven magnetization dynamics in magnetic nanostructures and plays an impor ... [Nature Phys. 8, 411 (2012)] published Wed May 2, 2012.

Spin-Flip Induced Magnetoresistance in Positionally Disordered Organic Solids

N. J. Harmon and M. E. Flatte
A model for magnetoresistance in positionally disordered organic materials is presented and solved using percolation theory. The model describes the effects of spin dynamics on hopping transport by considering changes in the effective density of hopping sites, a key quantity determining the properti ... [Phys. Rev. Lett. 108, 186602 ] published .

Dynamic Oscillations of Coupled Domain Walls

L. O'Brien, E. R. Lewis, A. Fernandez-Pacheco, D. Petit, R. P. Cowburn et al.
In domain wall (DW) excitation experiments, nonlinearity (NL) intrinsic to the DW dynamics is often hard to distinguish from perturbation due to the confining potential or DW distortion. Here we numerically investigate the dynamic oscillations of magnetostatically coupled DWs: a system well understo ... [Phys. Rev. Lett. 108, 187202 ] published .

Quantum point contact with large subband energy spacings

Y. J. Um, Y. H. Oh, M. Seo, S. Lee, Y. Chung et al.
Quantum point contact (QPC) with an extra metallic gate in between the split gates of a conventional QPC was fabricated and studied. Clear conductance quantization was observed at 4.2 K when a proper positive voltage was set to the middle gate of the QPC. The maximum energy spacing between the groun ... [Appl. Phys. Lett. 100, 183502 (2012)] published Thu May 3, 2012.

Interplay of bulk and edge states in transport of two-dimensional topological insulators

R. W. Reinthaler and E. M. Hankiewicz
We study transport in two-terminal metal/quantum spin Hall insulator/metal junctions. We show that the conductance signals originating from the bulk and the edge contributions are not additive. While for a long junction the transport is determined by the edge states contribution, for a short junctio ... [Phys. Rev. B 85, 165450 ] published .

Quantum Phase Slips in Superconducting Wires with Weak Inhomogeneities

Mihajlo Vanevic and Yuli V. Nazarov
Quantum phase slips are traditionally considered in diffusive superconducting wires which are assumed homogeneous. We present a definite estimate for the amplitude of phase slips that occur at a weak inhomogeneity in the wire where local resistivity is slightly increased. We model such a weak link a ... [Phys. Rev. Lett. 108, 187002 ] published .

Electron Waiting Times in Mesoscopic Conductors

Mathias Albert, Geraldine Haack, Christian Flindt, and Markus Buttiker
Electron transport in mesoscopic conductors has traditionally involved investigations of the mean current and the fluctuations of the current. A complementary view on charge transport is provided by the distribution of waiting times between charge carriers, but a proper theoretical framework for coh ... [Phys. Rev. Lett. 108, 186806 ] published .

Perfect coupling of light to surface plasmons by coherent absorption

Heeso Noh, Yidong Chong, A. Douglas Stone, and Hui Cao
We show theoretically that coherent light can be completely absorbed and transferred to surface plasmons in a two- or three-dimensional metallic nanostructure by exciting it with the time-reversed mode of the corresponding surface plasmon laser (spaser). The narrow-band perfect absorption is a gener ... [Phys. Rev. Lett. 108, 186805 ] published .

Probing the Topological Exciton Condensate via Coulomb Drag

M. P. Mink, H. T. C. Stoof, R. A. Duine, Marco Polini, and G. Vignale
The onset of exciton condensation in a topological insulator thin film was recently predicted. We calculate the critical temperature for this transition, taking into account screening effects. Furthermore, we show that the proximity to this transition can be probed by measuring the Coulomb drag resi ... [Phys. Rev. Lett. 108, 186402 ] published .

Rectification of thermal fluctuations in a chaotic cavity heat engine

Bjorn Sothmann, Rafael Sanchez, Andrew N. Jordan, and Markus Buttiker
We investigate the rectification of thermal fluctuations in a mesoscopic on-chip heat engine. The engine consists of a hot chaotic cavity capacitively coupled to a cold cavity which rectifies the excess noise and generates a directed current. The fluctuation-induced directed current depends on the e ... [Phys. Rev. B 85, 205301 ] published .

Universal line shape of the Kondo zero-bias anomaly in a quantum dot

Andrey V. Kretinin, Hadas Shtrikman, and Diana Mahalu
Encouraged by recent real-time renormalization group results, we carried out a detailed analysis of the nonequilibrium Kondo conductance observed in an InAs nanowire-based quantum dot and found them to be in excellent agreement. We show that in a wide range of biases the Kondo conductance zero-bias ... [Phys. Rev. B 85, 201301 ] published .

Mesoscopic Anderson box: Connecting weak to strong coupling

Dong E. Liu, Sebastien Burdin, Harold U. Baranger, and Denis Ullmo
We study the Anderson impurity problem in a mesoscopic setting, namely the Anderson box, in which the impurity is coupled to finite reservoir having a discrete spectrum and large sample-to-sample mesoscopic fluctuations. Note that both the weakly coupled and strong coupling Anderson impurity problem ... [Phys. Rev. B 85, 155455 ] published .

Local density of states in metal-topological superconductor hybrid systems

Marco Gibertini, Fabio Taddei, Marco Polini, and Rosario Fazio
We study by means of the recursive Green's function technique the local density of states of (finite and semi-infinite) multiband spin-orbit-coupled semiconducting nanowires in proximity to an s-wave superconductor and attached to normal-metal electrodes. When the nanowire is coupled to a normal ele ... [Phys. Rev. B 85, 144525 ] published .

Electron transport in suspended semiconductor structures with two-dimensional electron gas

A. G. Pogosov, M. V. Budantsev, E. Yu. Zhdanov, D. A. Pokhabov, A. K. Bakarov et al.
We study electron transport in suspended semiconductor microstructures fabricated from AlAs/GaAs membranes containing a high mobility two-dimensional electron gas. In quantizing magnetic fields, a reflection of edge current channels from the border of suspended area is observed resulting in the abse ... [Appl. Phys. Lett. 100, 181902 (2012)] published Mon Apr 30, 2012.

Kinetic Monte Carlo simulations and cross-sectional scanning tunneling microscopy as tools to investigate the heteroepitaxial capping of self-assembled quantum dots

J. G. Keizer, P. M. Koenraad, P. Smereka, J. M. Ulloa, A. Guzman et al.
The growth of self-assembled quantum dots has been intensively studied in the last decade. Despite substantial efforts, a number of details of the growth process remain unknown. The reason is the inability of current characterization techniques to image the growth process in real time. In this work, ... [Phys. Rev. B 85, 155326 ] published .

Colloidal nanocrystal quantum dot assemblies as artificial solids

Tobias Hanrath
The prospect of designing novel materials with electrical, optical, and magnetic properties by design has intrigued scientists and engineers for years. Building blocks for such artificial solids have emerged from recent advances in nanomaterial synthesis, characterization, and emerging understanding ... [J. Vac. Sci. Technol. A 30, 030802 (2012)] published Thu May 3, 2012.

Intermittent contact interaction between an atomic force microscope cantilever and a nanowire

I. Knittel, L. Ungewitter, and U. Hartmann
We investigate in theory and experiment the intermittent contact interaction between an atomic force microscope (AFM) cantilever and a nanowire under ambient conditions. The nanowire is modeled as a spring reacting instantaneously to any change of the force between the wire and the cantilever. This ... [J. Appl. Phys. 111, 094301 (2012)] published Wed May 2, 2012.

Multiphoton transitions in Josephson-junction qubits (Review Article)

S. N. Shevchenko, A. N. Omelyanchouk, and E. Il'ichev
Two basic physical models, a two-level system and a harmonic oscillator, are realized on the mesoscopic scale as coupled qubit and resonator. The realistic system includes moreover the electronics for controlling the distance between the qubit energy levels and their populations and to read out the ... [Low Temp. Phys. 38, 283 (2012)] published Fri Apr 27, 2012.

Nanoelectromechanics of superconducting weak links (Review Article)

A. V. Parafilo, I. V. Krive, R. I. Shekhter, and M. Jonson
Nanoelectromechanical effects in superconducting weak links are considered. Three different superconducting devices are studied: (i) a single-Cooper-pair transistor, (ii) a transparent SNS junction, and (iii) a single-level quantum dot coupled to superconducting electrodes. The electromechanical cou ... [Low Temp. Phys. 38, 273 (2012)] published Fri Apr 27, 2012.

Escape dynamics in moderately damped Josephson junctions (Review Article)

D. Massarotti, L. Longobardi, L. Galletti, D. Stornaiuolo, D. Montemurro et al.
The Josephson effect is a privileged access to the macroscopic quantum nature of superconductors. We review some ideas and experimental techniques on macroscopic quantum decay phenomena occurring in Josephson structures. The attention is mainly addressed to intermediate levels of dissipation which c ... [Low Temp. Phys. 38, 263 (2012)] published Fri Apr 27, 2012.

Gaussian quantum information

Christian Weedbrook, Stefano Pirandola, Raul Garcia-Patron, Nicolas J. Cerf, Timothy C. Ralph et al.
The science of quantum information has arisen over the last two decades centered on the manipulation of individual quanta of information, known as quantum bits or qubits. Quantum computers, quantum cryptography, and quantum teleportation are among the most celebrated ideas that have emerged from thi ... [Rev. Mod. Phys. 84, 621 ] published .