Condensed Matter

Destruction of N[e-acute]el order in the cuprates by electron doping

Ribhu K. Kaul, Max A. Metlitski, Subir Sachdev, and Cenke Xu
Motivated by the evidence in PrCeCuO and NdCeCuO of a magnetic quantum critical point at which Neel order is destroyed, we study the evolution with doping of the T=0 quantum phases of the electron-doped cuprates. At low doping, there is a metallic Neel state with small electron Fermi pockets, and th ... [Phys. Rev. B 78, 045110 (2008)] published Thu Jul 17, 2008.

Theory of a continuous Mott transition in two dimensions

T. Senthil
We study theoretically the zero-temperature phase transition in two dimensions from a Fermi liquid to a paramagnetic Mott insulator with a spinon Fermi surface. We show that the approach to the bandwidth-controlled Mott transition from the metallic side is accompanied by a vanishing quasiparticle re ... [Phys. Rev. B 78, 045109 (2008)] published Thu Jul 17, 2008.

Half-metallic finite zigzag single-walled carbon nanotubes from first principles

A. Mananes, F. Duque, A. Ayuela, M. J. Lopez, and J. A. Alonso
Density-functional calculations predict half-metallicity in zigzag single-walled carbon nanotubes of finite length with the two ends saturated with hydrogen. We have analyzed the change of the alpha- and beta-spin electronic gaps under the influence of an electric field applied along the nanotube ax ... [Phys. Rev. B 78, 035432 (2008)] published Thu Jul 17, 2008.

Electron-electron interactions in the vacuum polarization of graphene

Valeri N. Kotov, Bruno Uchoa, and A. H. Castro Neto
We discuss the effect of electron-electron interactions on the static polarization properties of graphene beyond RPA. Divergent self-energy corrections are naturally absorbed into the renormalized coupling constant alpha. We find that the lowest-order vertex correction, which is the first nontrivial ... [Phys. Rev. B 78, 035119 (2008)] published Thu Jul 17, 2008.

Turn-on dynamics and modulation response in semiconductor quantum dot lasers

Kathy Ludge, Moritz J. P. Bormann, Ermin Malic, Philipp Hovel, Matthias Kuntz et al.
We show that the dynamic response of electrically pumped semiconductor quantum dot lasers can be quantitatively understood by including the strongly nonlinear character of electron-electron scattering processes. The numerical simulations presented here combine a microscopic approach used for calcula ... [Phys. Rev. B 78, 035316 (2008)] published Thu Jul 17, 2008.

Incommensurability and atomic structure of c(2 x 2)N/Cu(100): A scanning tunneling microscopy study

T. Choi, C. D. Ruggiero, and J. A. Gupta
We use a scanning tunneling microscope operating in a low-temperature ultrahigh vacuum environment to study the atomic structure of single layer films of CuN grown on Cu(100). The c(2 x 2) lattice of CuN is incommensurate, with a lattice constant of 0.3720.001 nm that is 3% larger than the bare Cu( ... [Phys. Rev. B 78, 035430 (2008)] published Thu Jul 17, 2008.

Symmetry-induced tunneling in one-dimensional disordered potentials

E. Diez, F. Izrailev, A. Krokhin, and A. Rodriguez
A nontraditional mechanism of tunneling at macroscopic distances is proposed for a wave packet localized in a one-dimensional disordered potential with mirror symmetry, V(x)=V(x). Unlike quantum tunneling through a regular potential barrier, which occurs only at the energies lower than the barrier h ... [Phys. Rev. B 78, 035118 (2008)] published Thu Jul 17, 2008.

Maximally localized Wannier functions within the FLAPW formalism

F. Freimuth, Y. Mokrousov, D. Wortmann, S. Heinze, and S. Blugel
We report on the implementation of the Wannier Functions (WFs) formalism within the full-potential linearized augmented plane-wave method (FLAPW), suitable for bulk, film, and one-dimensional geometries. The details of the implementation, as well as results for the metallic SrVO, ferroelectric BaTiO ... [Phys. Rev. B 78, 035120 (2008)] published Thu Jul 17, 2008.

Erratum: Site-specific force-distance characteristics on NaCl(001): Measurements versus atomistic simulations [Phys. Rev. B [bold 74], 245426 (2006)]

M. A. Lantz, R. Hoffmann, A. S. Foster, A. Baratoff, H. J. Hug et al.
... [Phys. Rev. B 78, 039901 (2008)] published Thu Jul 17, 2008.

Kondo effect of single Co atoms adsorbed on Pb/Si(111) nanoislands

Xieqiu Zhang, Aidi Zhao, Kedong Wang, and Xudong Xiao
Using scanning tunneling spectroscopy, we have investigated the local electronic property change upon single Co atom adsorption on Pb nanoislands and/or films grown on a Si(111)-7 x 7 surface. The quantum well states formed on the clean Pb film were found to be locally destroyed by the adsorbed sing ... [Phys. Rev. B 78, 035431 (2008)] published Thu Jul 17, 2008.

Electronic structure of Ga[sub 1 - x]Cr[sub x]N and Si-doping effects studied by photoemission and x-ray absorption spectroscopy

G. S. Song, M. Kobayashi, J. I. Hwang, T. Kataoka, M. Takizawa et al.
The electronic structure of the magnetic semiconductor GaCrN, and the effect of Si doping on it have been investigated by photoemission and soft x-ray absorption spectroscopy. We have confirmed that Cr in GaN is predominantly trivalent when substituting for Ga and that Cr 3d states appear within the ... [Phys. Rev. B 78, 033304 (2008)] published Thu Jul 17, 2008.

Doubly degenerate orbital system in honeycomb lattice: Implication of orbital state in layered iron oxide

J. Nasu, A. Nagano, M. Naka, and S. Ishihara
We study a doubly degenerate orbital model on a honeycomb lattice. This is a model for orbital states in multiferroic layered iron oxides. The classical and quantum models are analyzed by spin-wave approximation, Monte Carlo simulation, and Lanczos method. A macroscopic number of degeneracy exists i ... [Phys. Rev. B 78, 024416 (2008)] published Thu Jul 17, 2008.

Modeling the Berezinskii-Kosterlitz-Thouless transition in NiGa[sub 2]S[sub 4]

Chyh-Hong Chern
In the two-dimensional superfluidity, the proliferation of the vortices and the antivortices results in a class of phase transition, the Berezinskii-Kosterlitz-Thouless (BKT) transition. This class of phase transition is also anticipated in the two-dimensional magnetic systems. However, its existenc ... [Phys. Rev. B 78, 020403 (2008)] published Thu Jul 17, 2008.

Shock-induced shear bands in an energetic molecular crystal: Application of shock-front absorbing boundary conditions to molecular dynamics simulations

M. J. Cawkwell, Thomas D. Sewell, Lianqing Zheng, and Donald L. Thompson
The response of the energetic molecular crystal cyclotrimethylene trinitramine (RDX) to the propagation of planar shock waves normal to (100) has been studied using large-scale molecular dynamics simulations that employ an accurate and transferable nonreactive potential. The propagation of the shock ... [Phys. Rev. B 78, 014107 (2008)] published Thu Jul 17, 2008.

Quantum mechanics of superconducting nanowires

S. Khlebnikov
In a short superconducting nanowire connected to bulk superconducting leads, quantum phase slips behave as a system of linearly (as opposed to logarithmically) interacting charges. This system maps onto quantum mechanics of a particle in a periodic potential. We show that, while the state with a hig ... [Phys. Rev. B 78, 014512 (2008)] published Thu Jul 17, 2008.

Effects of frustration on the anisotropic triangular lattice bosons

Jing-Yu Gan
We study the extended hard-core Bose-Hubbard model with nearest-neighbor interactions on a triangular lattice with spatial anisotropy by quantum Monte Carlo simulations. The effects of the geometric frustration or the anisotropic strength, represented by the ratio t/t between the intrachain nearest- ... [Phys. Rev. B 78, 014513 (2008)] published Thu Jul 17, 2008.

Antiferromagnetic ordering of energy levels for a spin ladder with four-spin cyclic exchange: Generalization of the Lieb-Mattis theorem

Tigran Hakobyan
The Lieb-Mattis theorem is generalized to an antiferromagnetic spin-ladder model with four-spin cyclic exchange interaction. We prove that for J>2 K, the antiferromagnetic ordering of energy levels takes place separately in two sectors, which remain symmetric and antisymmetric under the reflection ... [Phys. Rev. B 78, 012407 (2008)] published Thu Jul 17, 2008.

Structure and stability of Cd[sub 2]Nb[sub 2]O[sub 7] and Cd[sub 2]Ta[sub 2]O[sub 7] explored by ab initio calculations

Michael Fischer, Thomas Malcherek, Ulrich Bismayer, Peter Blaha, and Karlheinz Schwarz
Structural instabilities of CdNbO have been explored by all-electron ab initio calculations in the framework of density-functional theory. The calculated phonon-dispersion curve of the cubic high-temperature phase displays several modes with imaginary frequencies. A distortion according to a T mode ... [Phys. Rev. B 78, 014108 (2008)] published Thu Jul 17, 2008.

Interfacial elastic properties between a-Si and c-Si

Pier Luca Palla, Stefano Giordano, and Luciano Colombo
Interfaces between different media represent the most common structure in composite and complex materials, e.g., with applications in microelectronics and photovoltaics. We analyze the elastic properties of the -Si/ac-Si interface, which involves two completely different atomic structures. We prove ... [Phys. Rev. B 78, 012105 (2008)] published Thu Jul 17, 2008.

Current noise of a superconducting single-electron transistor coupled to a resonator

T. J. Harvey, D. A. Rodrigues, and A. D. Armour
We analyze the current and zero-frequency current noise properties of a superconducting single-electron transistor (SSET) coupled to a resonator, focusing on the regime where the SSET is operated in the vicinity of the Josephson quasiparticle resonance. We consider a range of coupling strengths and ... [Phys. Rev. B 78, 024513 (2008)] published Wed Jul 16, 2008.

Quantitative analysis of grain boundary properties in a generalized phase field model for grain growth in anisotropic systems

N. Moelans, B. Blanpain, and P. Wollants
A good choice of model formulation and model parameters is one of the most important and difficult aspects in mesoscale modeling and requires a systematic and quantitative analysis. In this paper, it is studied how the model parameters of a generalized phase field model affect the landscape of the f ... [Phys. Rev. B 78, 024113 (2008)] published Wed Jul 16, 2008.

Magnetic short-range correlations and quantum critical scattering in the non-Fermi liquid regime of URu[sub 2 - x]Re[sub x]Si[sub 2] (x = 0.2--0.6)

V. V. Krishnamurthy, D. T. Adroja, N. P. Butch, S. K. Sinha, M. B. Maple et al.
The spin dynamics of uranium ions in the non-Fermi liquid compounds URuReSi, for x=0.2 to 0.6, have been investigated using inelastic neutron scattering. The wave vector (q) dependence of the magnetic scattering provides evidence of short-range antiferromagnetic correlations at low temperatures for ... [Phys. Rev. B 78, 024413 (2008)] published Wed Jul 16, 2008.

Reversal mechanisms in perpendicularly magnetized nanostructures

Justin M. Shaw, Stephen E. Russek, Thomas Thomson, Michael J. Donahue, Bruce D. Terris et al.
We demonstrate that magnetic reversal in perpendicularly magnetized nanostructures is highly dependent on the nature and condition of the edges. To understand the impact of edge damage, we compare nanostructures created by ion milling to those prepared on prepatterned substrates. The size- and tempe ... [Phys. Rev. B 78, 024414 (2008)] published Wed Jul 16, 2008.

Metastability of multitwinned Ag nanorods: Molecular dynamics study

J. Monk, J. J. Hoyt, and D. Farkas
Nanoscale rods have been shown to exhibit a multiple twinned structure. The rods grow along a [110]-type crystallographic direction and have a pentagonal cross section with five (111) twins connecting the wire center to the corners of the pentagon. Here, we use molecular dynamics simulations with an ... [Phys. Rev. B 78, 024112 (2008)] published Wed Jul 16, 2008.

Liquid gallium-lead mixture spinodal, binodal, and excess thermodynamic properties

B. Grosdidier, S. M. Osman, and A. Ben Abdellah
A statistical mechanical based theory is developed for incorporating the effect of the long-range forces in Ga-Pb alloy. In particular, the simplified random-phase approximation is employed in conjunction with the Grosdidier et al. [Phys. Rev. B 72, 024207 (2005)] model for GaGa and PbPb interaction ... [Phys. Rev. B 78, 024205 (2008)] published Wed Jul 16, 2008.

Erratum: Enhanced triplet superconductivity in noncentrosymmetric systems [Phys. Rev. B [bold 75], 172511 (2007)]

Takehito Yokoyama, Seiichiro Onari, and Yukio Tanaka
... [Phys. Rev. B 78, 029902 (2008)] published Wed Jul 16, 2008.

Electron gas at the interface between two antiferromagnetic insulating manganites

M. J. Calderon, J. Salafranca, and L. Brey
We study theoretically the magnetic and electric properties of the interface between two antiferromagnetic and insulating manganites: LaCaMnO, a strong correlated insulator, and CaMnO, a band insulator. We find that a ferromagnetic and metallic electron gas is formed at the interface between the two ... [Phys. Rev. B 78, 024415 (2008)] published Wed Jul 16, 2008.

Lattice dynamics of vanadium: Inelastic x-ray scattering measurements

Alexey Bosak, Moritz Hoesch, Daniele Antonangeli, Daniel L. Farber, Irmengard Fischer et al.
We measured the phonon dispersions in vanadium along the principal symmetry directions using inelastic x-ray scattering. Our data complement previous results derived from thermal diffuse scattering and clearly reveal several phonon-dispersion anomalies, as well as pronounced variations of the phonon ... [Phys. Rev. B 78, 020301 (2008)] published Wed Jul 16, 2008.

Evidence of local superconductivity in granular Bi nanowires fabricated by electrodeposition

Mingliang Tian, Nitesh Kumar, Moses H. W. Chan, and Thomas E. Mallouk
An unusual enhancement of resistance (i.e., a superresistivity) below a certain characteristic temperature T was observed in granular Bi nanowires. This superresistive state was found to be dependent on the applied magnetic field as well as the excitation current. The suppression of T by magnetic fi ... [Phys. Rev. B 78, 045417 (2008)] published Wed Jul 16, 2008.

Electronic and vibronic interactions at weakly bound organic interfaces: The case of pentacene on graphite

Pavel B. Paramonov, Veaceslav Coropceanu, and Jean-Luc Bredas
The electronic and vibronic processes at the interface between a pentacene monolayer and a graphite surface were characterized using a combination of density-functional theory (DFT) and dynamic vibronic coupling simulations. The electronic interactions were evaluated at the DFT level first between t ... [Phys. Rev. B 78, 041403 (2008)] published Wed Jul 16, 2008.

Electric field effect on energy transfer monitored by bimolecular annihilation

C. Gadermaier, F. Grasse, S. Perissinotto, M. Graf, F. Galbrecht et al.
In conjugated polymers excited singlet states are known to dissociate into polarons upon application of an electric field. We show that for excitation intensities exceeding 100 [mu]J cm in polyfluorene, this is not the only mechanism of field-induced decrease in the singlet population. Bimolecular ... [Phys. Rev. B 78, 045207 (2008)] published Wed Jul 16, 2008.

Energy level alignment and chemical interaction at Alq[sub 3]/Co interfaces for organic spintronic devices

Y. Q. Zhan, M. P. de Jong, F. H. Li, V. Dediu, M. Fahlman et al.
The electronic structure of the interface between tris(8-hydroxyquinoline) aluminum (Alq) and cobalt was investigated by means of photoelectron spectroscopy. As demonstrated recently, this interface is characterized by efficient spin injection in organic spintronic devices. A strong interface dipole ... [Phys. Rev. B 78, 045208 (2008)] published Wed Jul 16, 2008.

Spin dynamics of two-dimensional electrons in a quantum Hall system probed by time-resolved Kerr rotation spectroscopy

D. Fukuoka, T. Yamazaki, N. Tanaka, K. Oto, K. Muro et al.
Time-resolved Kerr rotation spectroscopy under the radio frequency field to depolarize dynamic nuclear polarization reveals the intrinsic spin-relaxation time (T) and g factor of two-dimensional electrons in a quantum Hall system. Out-of-plane magnetic field increases the spin coherence drastically ... [Phys. Rev. B 78, 041304 (2008)] published Wed Jul 16, 2008.

Local atomic and electronic structures around Mg and Al dopants in LiNiO[sub 2] electrodes studied by XANES and ELNES and first-principles calculations

Kazuyoshi Tatsumi, Yusuke Sasano, Shunsuke Muto, Tomoko Yoshida, Tsuyoshi Sasaki et al.
We investigated the local atomic and electronic structures around the dopants Mg and Al in a LiNiO-based cathode material by the combination analysis of their K shell electron energy-loss near-edge structures, x-ray absorption near-edge structures, and first-principles calculations. The occupation s ... [Phys. Rev. B 78, 045108 (2008)] published Wed Jul 16, 2008.

First-principles study of adsorption, diffusion, and charge stability of metal adatoms on alkali halide surfaces

M. H. Hakala, O. H. Pakarinen, and A. S. Foster
In this work we have performed first-principles calculations based on the spin-polarized density-functional theory for the adsorption and diffusion of Au, Ag, and Pb atoms on NaCl(001), KCl(001), and KBr(001) surfaces. We consider also the influence of adatom charge on the adsorption and diffusion. ... [Phys. Rev. B 78, 045418 (2008)] published Wed Jul 16, 2008.

Controlling the torsional stochastic switching in phenylene ethynylene oligomer molecules by external electrostatic fields

Irina Petreska, LjupCo Pejov, and LjupCo Kocarev
First-principles molecular-orbital theory was used to predict the possibilities to control the single-molecule conductance switching by external electrostatic fields in the case of nondipolar phenylene ethynylene oligomer molecule. External field directed perpendicularly to the molecular plane was s ... [Phys. Rev. B 78, 045209 (2008)] published Wed Jul 16, 2008.

Vectorial four-wave mixing field dynamics from individual excitonic transitions

Jacek Kasprzak and Wolfgang Langbein
Degenerate four-wave mixing (FWM) from individual localized excitonic transitions is measured using a dual-polarization extension of heterodyne spectral interferometry. A fine-structure splitting (FSS) of the localized excitons of 2080 [mu]eV is observed, revealing a spatially anisotropic localizat ... [Phys. Rev. B 78, 041103 (2008)] published Wed Jul 16, 2008.

Length-dependent conductance and thermopower in single-molecule junctions of dithiolated oligophenylene derivatives: A density functional study

F. Pauly, J. K. Viljas, and J. C. Cuevas
We study theoretically the length dependence of both conductance and thermopower in metal-molecule-metal junctions made up of dithiolated oligophenylenes contacted to gold electrodes. We find that while the conductance decays exponentially with increasing molecular length, the thermopower increases ... [Phys. Rev. B 78, 035315 (2008)] published Wed Jul 16, 2008.

Kinetic electronic excitation of solids by fast-particle bombardment

Stefan Meyer, Christian Heuser, Detlef Diesing, and Andreas Wucher
The kinetic excitation of hot electrons and conduction-band vacancies following the impact of an energetic particle onto a solid surface was studied using metal-insulator-metal tunnel junctions. The top metal layer (polycrystalline silver) was bombarded by charged and neutral Ar projectiles of kinet ... [Phys. Rev. B 78, 035428 (2008)] published Wed Jul 16, 2008.

Diffusion piloted ordering in codeposited CoPt epitaxial layers: Experiment and quenched molecular dynamics simulations

O. Ersen, C. Goyhenex, and V. Pierron-Bohnes
This paper presents quenched molecular dynamics simulations of the vacancy behavior near the surface of an ordered CoPt alloy. The formation, migration, and activation energies are deduced for the different atoms (Co and Pt), moving in and between the different planes parallel to the surface. The mi ... [Phys. Rev. B 78, 035429 (2008)] published Wed Jul 16, 2008.

Anisotropy of the momentum matrix element, dichroism, and conduction-band dispersion relation of wurtzite semiconductors

S. Shokhovets, O. Ambacher, B. K. Meyer, and G. Gobsch
By comparison of calculated imaginary parts of the ordinary and extraordinary dielectric functions of wurtzite semiconductors near the band gap with experimental results, we demonstrate that the interband matrix elements E and E of the momentum operator parallel and perpendicular to the optic axis a ... [Phys. Rev. B 78, 035207 (2008)] published Wed Jul 16, 2008.

Phase transition and electronic state modification by lattice strain in 0.5-monolayer Sn/Cu(001)

Koichiro Yaji, Yuki Nara, Kan Nakatsuji, Takushi Iimori, Kazuma Yagyu et al.
We have studied the phase transition of 0.5-monolayer (ML) of Sn-adsorbed Cu(001) surface between (sqrt(2) x sqrt(2))R45 degrees structure at high-temperature phase and (3sqrt(2) x sqrt(2))R45 degrees structure at low-temperature phase, which was previously attributed to a charge-density wave (CDW ... [Phys. Rev. B 78, 035427 (2008)] published Wed Jul 16, 2008.

Exciton and hole spin dynamics in ZnO investigated by time-resolved photoluminescence experiments

D. Lagarde, A. Balocchi, P. Renucci, H. Carrere, F. Zhao et al.
The carrier spin dynamics in ZnO is investigated by time-resolved optical orientation experiments. We evidence a clear circular polarization of the donor-bound exciton luminescence in both ZnO epilayer and nonintentionally doped bulk ZnO. This allows us to measure the localized hole spin relaxation ... [Phys. Rev. B 78, 033203 (2008)] published Wed Jul 16, 2008.

Frustration-induced quantum phase transitions in a quasi-one-dimensional ferrimagnet: Hard-core boson map and the Tonks-Girardeau limit

R. R. Montenegro-Filho and M. D. Coutinho-Filho
We provide evidence of a superfluid-insulator transition (SIT) of magnons in a quasi-one-dimensional quantum ferrimagnet with isotropic competing antiferromagnetic spin interactions. This SIT occurs between two distinct ferrimagnetic phases due to the frustration-induced closing of the gap to a magn ... [Phys. Rev. B 78, 014418 (2008)] published Wed Jul 16, 2008.

Magnon-mediated thermal conductivity in the dimerized spin-gap compound BaCu[sub 2]V[sub 2]O[sub 8]

C. S. Lue, C. N. Kuo, D. S. Tasi, Y. K. Kuo, Zhangzhen He et al.
We have measured the thermal conductivity (kappa) of the quasi-one-dimensional spin-gap compound BaCuVO with heat flow parallel and perpendicular to the chain axis. Distinctive differences in the magnitude and temperature dependence between these directions have been observed. A weak but non-negligi ... [Phys. Rev. B 78, 012406 (2008)] published Wed Jul 16, 2008.

Large-scale Monte Carlo simulations of the three-dimensional XY spin glass

J. H. Pixley and A. P. Young
We study the XY spin glass by large-scale Monte Carlo simulations for sizes up to 24, down to temperatures below the transition temperature found in earlier work. The data for the larger sizes show more marginal behavior than that for the smaller sizes, indicating that the lower critical dimension i ... [Phys. Rev. B 78, 014419 (2008)] published Wed Jul 16, 2008.

Rattling motion of [sup 140]Ce(<--[sup 140]La) confined in the hexaboride cage

W. Sato, A. Shinohara, and Y. Ohkubo
Rattling motion of the probe Ce(<--La) confined in the B cage of LaB was observed by means of the time-differential perturbed angular correlation technique. The time scale of the motion is in the order of 10-10 s at room temperature. The activation energy of the slow motion at higher temperatures ( ... [Phys. Rev. B 78, 012301 (2008)] published Wed Jul 16, 2008.

All-optical generation and detection of subpicosecond ac spin-current pulses in GaAs

Brian A. Ruzicka, Karl Higley, Lalani K. Werake, and Hui Zhao
Subpicosecond ac spin-current pulses are generated optically in GaAs bulk and quantum wells at room temperature and at 90 K through quantum interference between one-photon and two-photon absorptions driven by two phase-locked ultrafast laser pulses that are both circularly polarized. The dynamics of ... [Phys. Rev. B 78, 045314 (2008)] published Tue Jul 15, 2008.

Tilted anisotropic Dirac cones in quinoid-type graphene and alpha-(BEDT-TTF)[sub 2]I[sub 3]

M. O. Goerbig, J.-N. Fuchs, G. Montambaux, and F. Piechon
We investigate a generalized two-dimensional Weyl Hamiltonian, which may describe the low-energy properties of mechanically deformed graphene and of the organic compound alpha-(BEDT-TTF)I [BEDT-TTF=bis(ethylenedithio)tetrathiafulvalene] under pressure. The associated dispersion has generically the f ... [Phys. Rev. B 78, 045415 (2008)] published Tue Jul 15, 2008.

Detailed scanning probe microscopy tip models determined from simultaneous atom-resolved AFM and STM studies of the TiO[sub 2](110) surface

Georg H. Enevoldsen, Henry P. Pinto, Adam S. Foster, Mona C. R. Jensen, Angelika Kuhnle et al.
The atomic-scale contrast in noncontact atomic force microscopy (nc-AFM) images is determined by the geometry and exact atomic structure of the tip apex. However, the tip state is an experimentally unknown parameter, and the lack of insight into the tip apex often limits the possibilities of extract ... [Phys. Rev. B 78, 045416 (2008)] published Tue Jul 15, 2008.

Analysis of the exciton-exciton interaction in semiconductor quantum wells

Christoph Schindler and Roland Zimmermann
The exciton-exciton interaction is investigated for quasi-two-dimensional quantum structures. A bosonization scheme is applied including the full spin structure. For generating the effective interaction potentials, the Hartree-Fock and Heitler-London approaches are improved by a full two-exciton cal ... [Phys. Rev. B 78, 045313 (2008)] published Tue Jul 15, 2008.

Effect of hydrogen molecules on the electronic transport through atomic-sized metallic junctions in the superconducting state

P. Makk, Sz. Csonka, and A. Halbritter
In this paper the interaction of hydrogen molecules with atomic-sized superconducting nanojunctions is studied. It is demonstrated by conductance histogram measurements that the superconductors niobium, tantalum, and aluminum show a strong interaction with hydrogen, whereas for lead a slight interac ... [Phys. Rev. B 78, 045414 (2008)] published Tue Jul 15, 2008.

Excitons in rolled up nanotubes of type-II semiconductor quantum wells: Theoretical study of a quasi-one-dimensional bosonic gas

Mehran Bagheri and Farshad Ebrahimi
The excitonic states and the quantum degenerate excitonic gas of spatially separated electron hole in an ideal rolled up nanotube of type-II semiconductor quantum wells with reverse bias configuration are studied theoretically. To illustrate the situation using the material constants appropriate to ... [Phys. Rev. B 78, 045312 (2008)] published Tue Jul 15, 2008.

Medium-energy ion-scattering study of strained holmium silicide nanoislands grown on silicon (100)

T. J. Wood, C. Eames, C. Bonet, M. B. Reakes, T. C. Q. Noakes et al.
We have used medium-energy ion scattering (MEIS) to quantitatively analyze the structure of holmium silicide islands grown on the Si(100) surface. Structure fitting to the experimental data unambiguously shows that the tetragonal silicide phase is present and not the hexagonal phase, which is associ ... [Phys. Rev. B 78, 035423 (2008)] published Tue Jul 15, 2008.

Effect of packing on the cohesive and electronic properties of methanofullerene crystals

J. M. Napoles-Duarte, M. Reyes-Reyes, J. L. Ricardo-Chavez, R. Garibay-Alonso, and R. Lopez-Sandoval
The crystal structure, cohesive energy, and electronic properties of bulk phases of the fullerene derivative [6, 6]-phenyl-C-butyric-acid-methyl-ester (PCBM) have been calculated using ab initio density-functional theory (DFT) techniques. We have only considered cubic and hexagonal crystal lattices ... [Phys. Rev. B 78, 035425 (2008)] published Tue Jul 15, 2008.

First-principles calculation of electronic polarization of III-V nanotubes

Jun Otsuka, Kikuji Hirose, and Tomoya Ono
A first-principles study of the electronic polarization of BN and AlN nanotubes and their graphitic sheets under an external electric field has been performed. We found that the polarization per atom of zigzag nanotubes increases with decreasing diameter while that of armchair nanotubes decreases. T ... [Phys. Rev. B 78, 035426 (2008)] published Tue Jul 15, 2008.

Exciton energy transfer between nanoparticles and nanowires

Pedro L. Hernandez-Martinez and Alexander O. Govorov
In this paper, we study the processes of exciton transfer in coupled nanoparticles and nanowires, and obtain convenient equations and numerical results for energy-transfer rates. For large distances, the energy-transfer rates are proportional to 1/d, where d is the nanoparticle-nanowire distance. Ou ... [Phys. Rev. B 78, 035314 (2008)] published Tue Jul 15, 2008.

Self-aligning atomic strings in surface-supported biomolecular gratings

Agustin Schiffrin, Joachim Reichert, Willi Auwarter, Gesine Jahnz, Yan Pennec et al.
We demonstrate the one-dimensional ordering of Co and Fe atoms employing supramolecular templates. Our low-temperature scanning tunneling microscopy observations reveal how individual adatoms spontaneously align with a preferred ~25 A next-neighbor spacing in self-assembled methionine nanogratings ... [Phys. Rev. B 78, 035424 (2008)] published Tue Jul 15, 2008.

Anisotropy in the electronic structure of V[sub 2]GeC investigated by soft x-ray emission spectroscopy and first-principles theory

Martin Magnuson, Ola Wilhelmsson, Maurizio Mattesini, Sa Li, Rajeev Ahuja et al.
The anisotropy of the electronic structure of ternary nanolaminate VGeC is investigated by bulk-sensitive soft x-ray emission spectroscopy. The measured polarization-dependent emission spectra of V L, C K, Ge M, and Ge M in VGeC are compared with those from monocarbide VC and pure Ge. The experiment ... [Phys. Rev. B 78, 035117 (2008)] published Tue Jul 15, 2008.

Field effect in manganite ultrathin films: Magnetotransport and localization mechanisms

I. Pallecchi, L. Pellegrino, E. Bellingeri, A. S. Siri, D. Marre et al.
In this paper, we report on field-effect experiments in LaSrMnO side-gate channels patterned on ultrathin epitaxial films having thickness ranging from 12 to 4 unit cells. Transport mechanisms and competition between phases, under the effect of electric and magnetic fields, as well as of other pertu ... [Phys. Rev. B 78, 024411 (2008)] published Tue Jul 15, 2008.

Nonlinear electrodynamics in layered superconductors

V. A. Yampol'skii, Sergey Savel'ev, A. L. Rakhmanov, and Franco Nori
We analyze theoretically the effect of a weak nonlinearity on the propagation of Josephson plasma waves in layered superconductors. The nonlinearity originates from the Josephson relation between the current density across superconducting layers and gauge-invariant phase difference of the order para ... [Phys. Rev. B 78, 024511 (2008)] published Tue Jul 15, 2008.

Bose-Einstein coherence in two-dimensional superfluid [sup 4]He

S. O. Diallo, J. V. Pearce, R. T. Azuah, J. W. Taylor, and H. R. Glyde
We present neutron-scattering measurements of the atomic momentum distribution and its Fourier transform, the one-body density matrix (OBDM), in liquid He films adsorbed in nanoporous MCM-41. The measurements were performed at liquid He temperatures T=0.3 K and T=2.3 K and saturated vapor pressure ... [Phys. Rev. B 78, 024512 (2008)] published Tue Jul 15, 2008.

Basic mechanisms of Frenkel pair recombinations in UO[sub 2] fluorite structure calculated by molecular dynamics simulations

L. Van Brutzel, A. Chartier, and J. P. Crocombette
In the present paper, the analysis of Frenkel pair recombinations is investigated by empirical-potentialmolecular dynamics simulations. Frenkel pairs with separation distance between the vacancy and the interstitial up to 1.5 times the lattice parameter have been studied. For each Frenkel pair, thei ... [Phys. Rev. B 78, 024111 (2008)] published Tue Jul 15, 2008.

Electric and magnetic modulation of fully strained dead layers in La[sub 0.67]Sr[sub 0.33]MnO[sub 3] films

Y. H. Sun, Y. G. Zhao, H. F. Tian, C. M. Xiong, B. T. Xie et al.
We report the electrical transport and magnetic properties of the dead layer of LaSrMnO grown on LaAlO substrate under the influence of magnetic field and electric voltage. The electrical resistance of the dead layer shows exponential decrease with both magnetic field and electric voltage, leading t ... [Phys. Rev. B 78, 024412 (2008)] published Tue Jul 15, 2008.

Molecular dynamics simulation of the six- to four-coordinate pressure-driven transition in MX nanocrystals: Mechanistic consequences of Sigma[sub 3] grain boundaries in the high-pressure starting structure

Benjamin J. Morgan
Constant-pressure molecular dynamics has been used to simulate the six- to four-coordinate downstroke pressure-driven phase transition in B1 nanocrystals. The nanocrystals considered have previously been formed in upstroke B3-->B1 simulations, giving them an amorphous surface region and interior Sig ... [Phys. Rev. B 78, 024110 (2008)] published Tue Jul 15, 2008.

Large-N estimates of universal amplitudes of the [openface C][openface P][sup N - 1] theory and comparison with a S = (1/2) square-lattice model with competing four-spin interactions

Ribhu K. Kaul and Roger G. Melko
We present computations of certain finite-size scaling functions and universal amplitude ratios in the large-N limit of the [openface C][openface P] field theory. We pay particular attention to the uniform susceptibility, the spin stiffness, and the specific heat. Field theoretic arguments have show ... [Phys. Rev. B 78, 014417 (2008)] published Tue Jul 15, 2008.

Voltage-controlled surface magnetization of itinerant ferromagnet Ni[sub 1 - x]Cu[sub x]

Igor V. Ovchinnikov and Kang L. Wang
We argue that surface magnetization of a metallic ferromagnet can be turned on and off isothermally by an applied voltage. For this, the material's electron subsystem must be close enough to the boundary between paramagnetic and ferromagnetic regions on the electron density scale. For the 3d series, ... [Phys. Rev. B 78, 012405 (2008)] published Tue Jul 15, 2008.

Scaling of entanglement support for matrix product states

L. Tagliacozzo, Thiago. R. de Oliveira, S. Iblisdir, and J. I. Latorre
The power of matrix product states to describe infinite-size translational-invariant critical spin chains is investigated. At criticality, the accuracy with which they describe ground-state properties of a system is limited by the size chi of the matrices that form the approximation. This limitation ... [Phys. Rev. B 78, 024410 (2008)] published Mon Jul 14, 2008.

Strong linewidth variation for spin-torque nano-oscillators as a function of in-plane magnetic field angle

K. V. Thadani, G. Finocchio, Z.-P. Li, O. Ozatay, J. C. Sankey et al.
We measure the microwave signals produced by spin-torque-driven magnetization dynamics excited by direct currents in patterned magnetic multilayer devices at room temperature as a function of the angle of a magnetic field applied in the sample plane. We find strong variations in the frequency linewi ... [Phys. Rev. B 78, 024409 (2008)] published Mon Jul 14, 2008.

Exotic magnetic structures in ultrathin helimagnetic holmium films

F. Cinti, A. Cuccoli, and A. Rettori
The problem of spin arrangement in ultrathin films of materials with competing medium-range interactions has been investigated by classical Monte Carlo simulations, assuming the model pertinent to bulk holmium. We find that in addition to distorted helical configurations at low temperature, unusual ... [Phys. Rev. B 78, 020402 (2008)] published Mon Jul 14, 2008.

Unusual thickness dependence of the superconducting transition of alpha -MoGe thin films

H. Tashiro, J. M. Graybeal, D. B. Tanner, E. J. Nicol, J. P. Carbotte et al.
Thin films of alpha-MoGe show progressively reduced T's as the thickness is decreased below 30 nm and the sheet resistance exceeds 100 Omega/[square, open]. We have performed far-infrared transmission and reflection measurements for a set of alpha-MoGe films to characterize this weakened supercondu ... [Phys. Rev. B 78, 014509 (2008)] published Mon Jul 14, 2008.

Stability of multielectron bubbles in liquid helium

Wei Guo, Dafei Jin, and Humphrey J. Maris
The stability of multielectron bubbles in liquid helium is investigated theoretically. We find that multielectron bubbles are unstable against fission whenever the pressure is positive. It is shown that for moving bubbles the Bernoulli effect can result in a range of pressures over which the bubbles ... [Phys. Rev. B 78, 014511 (2008)] published Mon Jul 14, 2008.

Ab initio study of the physical properties of gamma -Al[sub 2]O[sub 3]: Lattice dynamics, bulk properties, electronic structure, bonding, optical properties, and ELNES/XANES spectra

W. Y. Ching, Lizhi Ouyang, Paul Rulis, and Hongzhi Yao
Based on the most recently determined noncubic structure for gamma-AlO by Menendez-Proupin and Gutierrez, a comprehensive list of physical properties is investigated theoretically. These include lattice dynamics and phonon spectra, elastic constants and bulk structural parameters, electronic structu ... [Phys. Rev. B 78, 014106 (2008)] published Mon Jul 14, 2008.

Pairing symmetry of CeCoIn[sub 5] detected by in-plane torque measurements

H. Xiao, T. Hu, C. C. Almasan, T. A. Sayles, and M. B. Maple
In-plane torque measurements were performed on heavy fermion CeCoIn single crystals in the temperature T range 1.8 K<=T<=10 K and applied magnetic field H up to 14 T. The normal-state torque is given by tau[proportional]H(1+T/T) sin 4phi. The reversible part of the mixed-state torque, obtained aft ... [Phys. Rev. B 78, 014510 (2008)] published Mon Jul 14, 2008.

Phase-dependent electronic specific heat of mesoscopic Josephson junctions

Hassan Rabani, Fabio Taddei, Olivier Bourgeois, Rosario Fazio, and Francesco Giazotto
We study the influence of superconducting correlations on the electronic specific heat in a diffusive superconductor-normal metal-superconductor Josephson junction. We present a description of this system in the framework of the diffusive-limit Green's function theory, taking into account finite tem ... [Phys. Rev. B 78, 012503 (2008)] published Mon Jul 14, 2008.

Growth and shape transition of small silicon self-interstitial clusters

Sangheon Lee and Gyeong S. Hwang
The growth behavior of small self-interstitial clusters in crystalline Si is presented based on extensive combined Metropolis Monte Carlo, tight-binding molecular dynamics, and density-functional theory calculations. New stable structures for small interstitial clusters (I,5<=n<=16) are determined, ... [Phys. Rev. B 78, 045204 (2008)] published Mon Jul 14, 2008.

Electron spin resonance and microwave magnetoresistance in Ge:Mn thin films

R. Morgunov, M. Farle, M. Passacantando, L. Ottaviano, and O. Kazakova
We report a study of resonant and nonresonant microwave absorption in germanium thin films (t=120 nm) implanted with manganese to a concentration of x=28 at. %. The germanium matrix contains MnGe precipitates, Mn-rich ferromagnetic nanoclusters, and diluted Mn ions. Electron spin resonances (ESR) ... [Phys. Rev. B 78, 045206 (2008)] published Mon Jul 14, 2008.

Effects of different geometries on the conductance, shot noise, and tunnel magnetoresistance of double quantum dots

Ireneusz Weymann
The spin-polarized transport through a coherent strongly coupled double quantum dot (DQD) system is analyzed theoretically in the sequential and cotunneling regimes. Using the real-time diagrammatic technique, we analyze the current, differential conductance, shot noise, and tunnel magnetoresistance ... [Phys. Rev. B 78, 045310 (2008)] published Mon Jul 14, 2008.

Insulator-metal transition and anomalous sign reversal of the dominant charge carriers in perovskite BaTiO[sub 3 - delta]

T. Kolodiazhnyi
Dc resistivity, magnetic susceptibility, and Hall and Seebeck coefficients were measured in the 2400 K range on perovskite BaTiO single crystals with electron concentration of 9.8 x 103.5 x 10 cm. The insulator-metal transition in BaTiO was found at critical electron concentration n[approximate]1.6 ... [Phys. Rev. B 78, 045107 (2008)] published Mon Jul 14, 2008.

Debye relaxation in high magnetic fields

J. S. Brooks, R. Vasic, A. Kismarahardja, E. Steven, T. Tokumoto et al.
Dielectric relaxation is universal in characterizing polar liquids and solids, insulators, and semiconductors, and the theoretical models are well developed. However, in high magnetic fields, previously unknown aspects of dielectric relaxation can be revealed and exploited. Here, we report low-tempe ... [Phys. Rev. B 78, 045205 (2008)] published Mon Jul 14, 2008.

Impact of visible light illumination on ultraviolet emission from ZnO nanocrystals

S. S. Kurbanov, G. N. Panin, T. W. Kim, and T. W. Kang
The influence of a visible Ar-laser (488 nm) illumination on photoluminescence (PL) from ZnO nanocrystals excited by He-Cd laser (325 nm) at various excitation intensities and temperatures was investigated. A reversible quenching of the UV near-band-edge emission under Ar-laser illumination was obse ... [Phys. Rev. B 78, 045311 (2008)] published Mon Jul 14, 2008.

Hydrogen storage by spillover on graphene as a phase nucleation process

Yu Lin, Feng Ding, and Boris I. Yakobson
Hydrogen chemisorption on graphene receptor-substrate is of great interest for energy storage. However, it is difficult to reconcile with a single H atom binding to carbon being weaker than it is within initial molecular H. This paradox is resolved by presenting the process as phase nucleation in th ... [Phys. Rev. B 78, 041402 (2008)] published Mon Jul 14, 2008.

Competition between Pomeranchuk instabilities in the nematic and hexatic channels in a two-dimensional spinless Fermi fluid

Daniel G. Barci, Marta Trobo, Victoria Fernandez, and Luis E. Oxman
We study the competition between the nematic and the hexatic phases of a two-dimensional spinless Fermi fluid near Pomeranchuk instabilities. We show that the general phase diagram of this theory contains a bicritical point where two second-order lines and a first-order nematic/hexatic phase transit ... [Phys. Rev. B 78, 035114 (2008)] published Mon Jul 14, 2008.

Applying matrix product operators to model systems with long-range interactions

Gregory M. Crosswhite, A. C. Doherty, and Guifre Vidal
An algorithm is presented which computes a translationally invariant matrix product state approximation of the ground state of an infinite one-dimensional (1D) system. It does this by embedding sites into an approximation of the infinite environment of the chain, allowing the sites to relax and then ... [Phys. Rev. B 78, 035116 (2008)] published Mon Jul 14, 2008.

Microscopic evidence for role of oxygen in luminescence of Er[sup 3+] ions in Si: Two-color and pump-probe spectroscopy

S. Minissale, N. Q. Vinh, W. de Boer, M. S. Bresler, and T. Gregorkiewicz
Influence of oxygen on optical activity and thermal stability of the 1.5 [mu]m emission of Er ions in Si is well documented. Here we support this predominantly phenomenological notion with microscopic evidence. Using two-color and pump-probe spectroscopy with a free-electron laser we establish a di ... [Phys. Rev. B 78, 035313 (2008)] published Mon Jul 14, 2008.

Coexistence of distinct charge fluctuations in theta-(BEDT-TTF)[sub 2]X

S. Nishimoto, M. Shingai, and Y. Ohta
Using the Lanczos exact-diagonalization and density-matrix renormalization-group methods, we study the extended Hubbard model at quarter filling defined on the anisotropic triangular lattice. We focus on charge ordering (CO) phenomena induced by onsite and intersite Coulomb interactions. We determin ... [Phys. Rev. B 78, 035113 (2008)] published Mon Jul 14, 2008.

Transport properties of quantum dot arrays

Jianwei Cai and G. D. Mahan
The model of crystalline arrays of quantum dots is studied with dynamical mean-field theory. Low-temperature transport coefficients are calculated. The material is found to be metallic with a large Seebeck coefficient, which has a good promise for thermoelectric applications. ... [Phys. Rev. B 78, 035115 (2008)] published Mon Jul 14, 2008.

Transport through single-wall metallic carbon nanotubes in the cotunneling regime

I. Weymann, J. Barnas, and S. Krompiewski
Using the real-time diagrammatic technique and taking into account both the sequential and cotunneling processes, we analyze the transport properties of single-wall metallic carbon nanotubes coupled to nonmagnetic and ferromagnetic leads in the full range of parameters. In particular, considering th ... [Phys. Rev. B 78, 035422 (2008)] published Mon Jul 14, 2008.

Origin of ferromagnetism of MnSi[sub 1.7] nanoparticles in Si: First-principles calculations

Shin Yabuuchi, Hiroyuki Kageshima, Yukinori Ono, Masao Nagase, Akira Fujiwara et al.
The origin of the magnetism of MnSi nanoparticles in Si is investigated using the first-principles calculations: bulk and interface effects are considered. The bulk magnetic property is expected to be affected by stoichiometry, strain, and charge accumulation. Stoichiometry and charge accumulation i ... [Phys. Rev. B 78, 045307 (2008)] published Fri Jul 11, 2008.

Two-step versus one-step model of the interpolarization conversion and statistics of CdSe/ZnSe quantum dot elongations

A. V. Koudinov, B. R. Namozov, Yu. G. Kusrayev, S. Lee, M. Dobrowolska et al.
The magneto-optical interpolarization conversions by a layer of quantum dots have been investigated. Various types of polarization response of the sample were observed as a function of external magnetic field and of the orientation of the sample. The full set of experimental dependences is analyzed ... [Phys. Rev. B 78, 045309 (2008)] published Fri Jul 11, 2008.

Temperature-induced spin-coherence dissipation in quantum dots

F. G. G. Hernandez, A. Greilich, F. Brito, M. Wiemann, D. R. Yakovlev et al.
The temperature dependence of electron-spin coherence in singly negatively charged (In,Ga)As/GaAs quantum dots is studied by time-resolved Faraday rotation. The decoherence time T is constant on the microsecond scale for temperatures below 15 K; for higher temperatures it shows a surprisingly sharp ... [Phys. Rev. B 78, 041303 (2008)] published Fri Jul 11, 2008.

Statistics of measurement of noncommuting quantum variables: Monitoring and purification of a qubit

Hongduo Wei and Yuli V. Nazarov
We address continuous weak linear quantum measurement and argue that it is best understood in terms of statistics of the outcomes of the linear detectors measuring a quantum system, for example, a qubit. We mostly concentrate on a setup consisting of a qubit and three independent detectors that simu ... [Phys. Rev. B 78, 045308 (2008)] published Fri Jul 11, 2008.

Crystal-field excitations in NiO studied with hard x-ray resonant inelastic x-ray scattering at the Ni K edge

Simo Huotari, Tuomas Pylkkanen, Gyorgy Vanko, Roberto Verbeni, Pieter Glatzel et al.
Charge-neutral dd excitations in NiO have been studied using resonant inelastic x-ray scattering (RIXS) at the quadrupolar pre-edge of the Ni K absorption edge (8331 eV) with an energy resolution of 250 meV. The results agree well with calculations performed using the atomic multiplet model for the ... [Phys. Rev. B 78, 041102 (2008)] published Fri Jul 11, 2008.

Control of non-Markovian effects in the dynamics of polaritons in semiconductor microcavities

F. J. Rodriguez, L. Quiroga, C. Tejedor, M. D. Martin, L. Vina et al.
We report on time-resolved photoluminescence from semiconductor microcavities showing that an optically controllable mechanism exists to turn on and off memory effects in a polariton system. By increasing the laser pumping pulse intensity resonantly exciting the upper polariton branch, we observe re ... [Phys. Rev. B 78, 035312 (2008)] published Fri Jul 11, 2008.

Structure of the metallic Si(001) surface at high temperatures: Synchrotron x-ray scattering measurements

Yongsam Kim, Cheolho Jeon, S. H. Uhm, C. C. Hwang, N. D. Kim et al.
The structure of the metallic Si(001) surface above 900 K was investigated by synchrotron x-ray scattering. Above 900 K, the (2, 1) integer-order surface peak decreases anomalously while the (3/2, 0) reconstruction order peak increases. These results together with the behavior of the crystal truncat ... [Phys. Rev. B 78, 033303 (2008)] published Fri Jul 11, 2008.

States of a two-dimensional photonic crystal in the presence of spatial modulation and anisotropy: A perturbative approach

G. Alagappan, X. W. Sun, and M. B. Yu
This paper presents an analytic study on the photonic states of a two-dimensional photonic crystal. Degenerate states in the absence of spatial modulation are systematically classified and the states within the same class behave similarly when the spatial modulation or the material's anisotropy is s ... [Phys. Rev. B 78, 035112 (2008)] published Fri Jul 11, 2008.

Atomic oxygen adsorption and incipient oxidation of the Pb(111) surface: A density-functional theory study

Bo Sun, Ping Zhang, Zhigang Wang, Suqing Duan, Xian-Geng Zhao et al.
We study the atomic oxygen adsorption on Pb(111) surface by using density-functional theory within the generalized gradient approximation and a supercell approach. The atomic and energetic properties of purely on-surface and subsurface oxygen structures at the Pb(111) surface are systematically inve ... [Phys. Rev. B 78, 035421 (2008)] published Fri Jul 11, 2008.

Simulations of indentation-induced phase transformations in crystalline and amorphous silicon

V. I. Ivashchenko, P. E. A. Turchi, and V. I. Shevchenko
The pressure- and indentation-induced phase transformations in crystalline (cd) and amorphous (a) silicon are studied by using molecular dynamics simulations based on the modified Tersoff potential. The sps tight-binding scheme is employed to gain insight into the origin of the change in conductivit ... [Phys. Rev. B 78, 035205 (2008)] published Fri Jul 11, 2008.

Comparative NMR investigation of the Re-based borides

C. S. Lue, Y. F. Tao, and T. H. Su
We report a systematic study of the rhenium-based borides, ReB, ReB, and ReB, by means of the B nuclear magnetic resonance (NMR) spectroscopy. While ReB and ReB are superconductors, ReB exhibits no superconducting signature but is of current interest due to its superhard mechanical property. Since t ... [Phys. Rev. B 78, 033107 (2008)] published Fri Jul 11, 2008.

Many-flavor electron gas approach to electron-hole drops

G. J. Conduit
A many-flavor electron gas (MFEG) is analyzed, such as could be found in a multivalley semiconductor or semimetal. Using the rederived polarizability for the MFEG, an exact expression for the total energy of a uniform MFEG in the many-flavor approximation is found; the interacting energy per particl ... [Phys. Rev. B 78, 035111 (2008)] published Fri Jul 11, 2008.

Theory and design of quantum cascade lasers in (111) n-type Si/SiGe

A. Valavanis, L. Lever, C. A. Evans, Z. Ikonic, and R. W. Kelsall
Although most work toward the realization of group IV quantum cascade lasers (QCLs) has focused on valence-band transitions, there are many desirable properties associated with the conduction band. We show that the commonly cited shortcomings of n-type Si/SiGe heterostructures can be overcome by mov ... [Phys. Rev. B 78, 035420 (2008)] published Fri Jul 11, 2008.

Collective plasmonic modes in two-dimensional periodic arrays of metal nanoparticles

Yu-Rong Zhen, Kin Hung Fung, and C. T. Chan
We investigate the collective plasmonic modes of metal nanoparticles in periodic two-dimensional (2D) arrays within a point-dipole description. The dynamic dispersion relations of the 2D arrays are obtained through a method which gives an effective polarizability describing the collective response o ... [Phys. Rev. B 78, 035419 (2008)] published Fri Jul 11, 2008.

Many-body effects on optical carrier cooling in intrinsic semiconductors at low lattice temperatures

Danhong Huang and P. M. Alsing
Based on the coupled density and energy balance equations, a dynamical model is proposed for exploring many-body effects on optical carrier cooling (not lattice cooling) in steady state in comparison with the earlier findings of current-driven carrier cooling in doped semiconductors [X. L. Lei and C ... [Phys. Rev. B 78, 035206 (2008)] published Fri Jul 11, 2008.

Effect of pressure on the electric-field-induced resistance switching of VO[sub 2] planar-type junctions

Joe Sakai and Makio Kurisu
VO thin-film planar-type junctions with the size of 1500 [mu]m in width and 10 [mu]m in length were fabricated on AlO (0001) substrates, and the electric-field-induced resistance switching (EIRS) characteristics were investigated at hydrostatic pressures up to 2 GPa and room temperature. The resis ... [Phys. Rev. B 78, 033106 (2008)] published Fri Jul 11, 2008.

Structure and properties of the kagome compound YBaCo[sub 3]AlO[sub 7]

M. Valldor, N. Hollmann, J. Hemberger, and J. A. Mydosh
Large single crystals of YBaCoAlO were synthesized in a floating-zone furnace. Powder and single-crystal x-ray data confirm that the structure belongs to the swedenborgite compound family (P6mc, a=6.28098(3) A, and c=10.21200(5) A). YBaCoAlO can reversibly absorb/desorb oxygen up to about O accord ... [Phys. Rev. B 78, 024408 (2008)] published Fri Jul 11, 2008.

Relaxor ferroelectric behavior in Ca-doped TbMnO[sub 3]

N. Mufti, A. A. Nugroho, G. R. Blake, and T. T. M. Palstra
We have studied the effect of Ca-doping in single-crystal TbCaMnO(x<=0.1) on the crystal and magnetic structure, magnetocapacitance, and electric polarization. For low doping (x=0.05), the presence of Mn ions gives rise to a state with behavior resembling that of a relaxor ferroelectric. The coheren ... [Phys. Rev. B 78, 024109 (2008)] published Fri Jul 11, 2008.

Flux tubes and the type-I/type-II transition in a superconductor coupled to a superfluid

Mark G. Alford and Gerald Good
We analyze magnetic-flux tubes at zero temperature in a superconductor that is coupled to a superfluid via both density and gradient (entrainment) interactions. The example we have in mind is high-density nuclear matter, which is a proton superconductor and a neutron superfluid, but our treatment is ... [Phys. Rev. B 78, 024510 (2008)] published Fri Jul 11, 2008.

Structure and melting behavior of classical bilayer crystals of dipoles

Xin Lu, Chang-Qin Wu, Andrea Micheli, and Guido Pupillo
We study the structure and melting of a classical bilayer system of dipoles in a setup where the dipoles are oriented perpendicular to the planes of the layers and the density of dipoles is the same in each layer. Due to the anisotropic character of the dipole-dipole interactions, we find that the g ... [Phys. Rev. B 78, 024108 (2008)] published Fri Jul 11, 2008.

Properties of Pt-supported Co nanomagnets from relativistic density functional theory calculations

Adriano Mosca Conte, Stefano Fabris, and Stefano Baroni
The electronic, structural, and magnetic properties of Co-based low-dimensional nanostructures supported by Pt surfaces are investigated using computer simulations based on density functional theory. The effects of the local orientation of the magnetization, including the magnetic anisotropy energy, ... [Phys. Rev. B 78, 014416 (2008)] published Fri Jul 11, 2008.

Coherent-to-semi-coherent transition of precipitates in niobium-hydrogen thin films

Kai Northemann and Astrid Pundt
Nucleation and growth in thin films are studied by using niobium-hydrogen (Nb-H) as model system. Hydride precipitation in thin films results in local surface topography changes that can be monitored by scanning tunneling microscopy. The local film expansion can be used to detect hydride precipitate ... [Phys. Rev. B 78, 014105 (2008)] published Fri Jul 11, 2008.

Numerical study of quantum vortex phase diagram in two-dimensional superconductors

Kiyokazu Myojin, Ryusuke Ikeda, and Shigeru Koikegami
Vortex phase diagrams of weakly disordered two-dimensional (2D) superconductors under a magnetic field perpendicular to the plane are numerically studied based on a recent development on the corresponding issue in three-dimensional (3D) systems with a low density of columnar defects at high temperat ... [Phys. Rev. B 78, 014508 (2008)] published Fri Jul 11, 2008.

Eigenvalue distributions of correlated multichannel transfer matrices in strongly scattering systems

Rudolf Sprik, Arnaud Tourin, Julien de Rosny, and Mathias Fink
We experimentally study the effects of correlations in the propagation of ultrasonic waves in water from a multielement source to a multielement detector through a strongly scattering system of randomly placed vertical rods. Due to the strong scattering, the wave transport in the sample is in the di ... [Phys. Rev. B 78, 012202 (2008)] published Fri Jul 11, 2008.

Cleaving-temperature dependence of layered-oxide surfaces. (arXiv:0807.2672v1 [cond-mat.str-el])

ePrint arXiv http://arXiv.org/

Ratchet effect in inhomogeneous inertial systems: I. Adiabatic case. (arXiv:0807.2725v2 [cond-mat.stat-mech])

ePrint arXiv http://arXiv.org/

Quantum magnetotransport in a graphene monolayer in the presence of spatially modulated electric and magnetic fields. (arXiv:0807.2746v1 [cond-mat.mes-hall])

ePrint arXiv http://arXiv.org/

Observation of new quantum interference effect in solids. (arXiv:0807.2747v1 [cond-mat.mes-hall])

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Hot spots and waves in Bi2Sr2CaCu2O8 intrinsic Josephson junction stacks -a study by Low Temperature Scanning Laser Microscopy. (arXiv:0807.2749v1 [cond-mat.supr-con])

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Is charge noise in single electron transistors and charge qubits caused by metallic grains?. (arXiv:0807.2751v1 [cond-mat.mes-hall])

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Fast fluorescence dynamics in nonratiometric calcium indicators. (arXiv:0807.2756v1 [physics.bio-ph])

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Phase Diagram of Vortices in High-T_c Superconductors with a Melting Line in the deep H_{c2} Region. (arXiv:0807.2757v1 [cond-mat.supr-con])

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Weakly interacting graphene on a metal: Dirac cones and minigaps for C/Ir(111). (arXiv:0807.2770v1 [cond-mat.mtrl-sci])

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The Berry phase: a topological test for the spectrum structure of frustrated quantum spin systems. (arXiv:0807.2720v1 [cond-mat.str-el])

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Attractive and repulsive cracks in a heterogeneous material. (arXiv:0807.2719v1 [cond-mat.mtrl-sci])

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Delayed currents and interaction effects in mesoscopic capacitors. (arXiv:0807.2717v1 [cond-mat.mes-hall])

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