Effect of crystal-field splitting and interband hybridization on the metal-insulator transitions of strongly correlated systems
Alexander I. Poteryaev, Michel Ferrero, Antoine Georges, and Olivier Parcollet
We investigate a quarter-filled two-band Hubbard model involving a crystal-field splitting, which lifts the orbital degeneracy as well as an interorbital hopping (interband hybridization). Both terms are relevant to the realistic description of correlated materials such as transition-metal oxides. T ... [Phys. Rev. B 78, 045115 (2008)] published Wed Jul 23, 2008.
Time-dependent Gutzwiller theory of pairing fluctuations in the Hubbard model
G. Seibold, F. Becca, and J. Lorenzana
We present a method to compute pairing fluctuations on top of the Gutzwiller approximation (GA). Our investigations are based on a charge-rotational invariant GA energy functional which is expanded up to second order in the pair fluctuations. Equations of motion for the fluctuations lead to a renorm ... [Phys. Rev. B 78, 045114 (2008)] published Wed Jul 23, 2008.
High-temperature annealing behavior of deep levels in 1 MeV electron irradiated p-type 6H-SiC
Giovanni Alfieri and Tsunenobu Kimoto
We report on the thermal stability of deep levels detected after 1 MeV electron irradiated p-type 6H-SiC. The investigation was performed by deep level transient spectroscopy, and an isochronal annealing series was carried out in the 3732073 K temperature range. We found seven traps located betwee ... [Appl. Phys. Lett. 93, 032108 (2008)] published Wed Jul 23, 2008.
Stretched-exponential a-Si:H/c-Si interface recombination decay
Stefaan De Wolf, Sara Olibet, and Christophe Ballif
The electronic properties of hydrogenated amorphous silicon (a-Si:H) relax following stretched exponentials. This phenomenon was explained in the past by dispersive hydrogen diffusion, or by retrapping included hydrogen motion. In this letter, the authors report that the electronic passivation prope ... [Appl. Phys. Lett. 93, 032101 (2008)] published Wed Jul 23, 2008.
Separation of electronic and ionic conductivity in mixed conductors from the ac response: Application to Pr[sub 0.56]Bi[sub 0.04]Li[sub 0.2]TiO[sub 3]
Mario-Fidel Garcia-Sanchez, Nestor Fernandez, Maria-Luisa Martinez-Sarrion, Lourdes Mestres, Floiran Fernandez-Gutierrez et al.
A method has been developed for separation of ionic and electronic conductivity in mixed conductors. The procedure is accomplished by using blocking electrodes and the KramersKronig relations for separating the dc conductivity from total response. This method was applied to lithium inserted and dein ... [Appl. Phys. Lett. 93, 034105 (2008)] published Wed Jul 23, 2008.
Carrier dynamics of type-II InAs/GaAs quantum dots covered by a thin GaAs[sub 1 - x]Sb[sub x] layer
Wen-Hao Chang, Yu-An Liao, Wei-Ting Hsu, Ming-Chih Lee, Pei-Chin Chiu et al.
Carrier dynamics of InAs/GaAs quantum dots (QDs) covered by a thin GaAsSb layer were investigated by time-resolved photoluminescence (PL). Both the power dependence of PL peak shift and the long decay time constants confirm the type-II band alignment at the GaAsSbInAs interface. Different recombinat ... [Appl. Phys. Lett. 93, 033107 (2008)] published Wed Jul 23, 2008.
Bias-controlled spin polarization in quantum wires
T.-M. Chen, A. C. Graham, M. Pepper, I. Farrer, and D. A. Ritchie
We demonstrate that a source-drain bias creates a fully spin-polarized current as the 0.25(2e/h) plateau in quantum wires even in zero magnetic field. When a source-drain bias lifts the momentum degeneracy, the dc measurements show that it is possible to achieve a unidirectional ferromagnetic order ... [Appl. Phys. Lett. 93, 032102 (2008)] published Wed Jul 23, 2008.
Resistance-pressure sensitivity and a mechanism study of multiwall carbon nanotube networks/poly(dimethylsiloxane) composites
C. H. Hu, C. H. Liu, L. Z. Chen, Y. C. Peng, and S. S. Fan
In this work, we explored the electrical resistance-pressure sensitivity of multiwall carbon nanotube (MWNT) networks/poly(dimethylsiloxane) (PDMS) composites and proposed a deformation-induced property transition mechanism of the nanotubes to explain this behavior. The thermoelectric coefficients o ... [Appl. Phys. Lett. 93, 033108 (2008)] published Wed Jul 23, 2008.
Evidence of low interface trap density in GeO[sub 2]/Ge metal-oxide-semiconductor structures fabricated by thermal oxidation
Hiroshi Matsubara, Takashi Sasada, Mitsuru Takenaka, and Shinichi Takagi
We have fabricated GeO/Ge metal-oxide-semiconductor (MOS) structures by direct thermal oxidation of Ge substrates. The interface trap density (D) of Al/GeO/Ge MOS structures, measured by the low temperature conductance method including the effect of the surface potential fluctuation, is found to be ... [Appl. Phys. Lett. 93, 032104 (2008)] published Wed Jul 23, 2008.
Transient carrier transfer in tunnel injection structures
V. G. Talalaev, J. W. Tomm, N. D. Zakharov, P. Werner, U. Gosele et al.
InGaAs tunnel injection nanostructures consisting of a single quantum well as injector and a quantum dot layer as emitter are studied by time-resolved photoluminescence spectroscopy. The quantum dot photoluminescence undergoes substantial changes when proceeding from direct quantum dot excitation to ... [Appl. Phys. Lett. 93, 031105 (2008)] published Wed Jul 23, 2008.
Quantum-size effects in ultrathin Mg films
N. Binggeli and M. Altarelli
Recent experiments on the oxidation of ultrathin Mg films have revealed the existence of a correlation between surface reactivity and quantum-size effects. Using ab initio density-functional calculations, we have investigated the electronic properties of epitaxial Mg(0001) films, 517 atomic-layer th ... [Phys. Rev. B 78, 035438 (2008)] published Wed Jul 23, 2008.
Properties of a class of topological phase transitions
Zi Cai, Shu Chen, Supeng Kou, and Yupeng Wang
The properties of a class of topological quantum phase transition (TQPT) are analyzed based on a model proposed by Haldane. We study the effect of finite temperature on this phase transition. We have found that finite temperature would drive this TQPT to be a crossover, while it is stable against th ... [Phys. Rev. B 78, 035123 (2008)] published Wed Jul 23, 2008.
Electronic transport of Au-adsorbed Si(111)-sqrt(3) x sqrt(3)-Ag: Metallic conduction and localization
Canhua Liu, Iwao Matsuda, Shinya Yoshimoto, Taizo Kanagawa, and Shuji Hasegawa
The electrical conductance of Au-adsorbed Si(111)-sqrt(3) x sqrt(3)-Ag surface was studied as a function of temperature (110300 K) by a method of micro-four-point probe. In the pristine surface without Au adsorbates, the surface electrical conductance was inversely proportional to the temperature, i ... [Phys. Rev. B 78, 035326 (2008)] published Wed Jul 23, 2008.
Land[e-acute]-like formula for the g factors of hole-nanowire subband edges
D. Csontos, U. Zulicke, P. Brusheim, and H. Q. Xu
We have analyzed theoretically the Zeeman splitting of hole-quantum-wire subband edges. As is typical for any bound state, their g factor depends on both an intrinsic g factor of the material and an additional contribution arising from a finite bound-state orbital angular momentum. We discuss the qu ... [Phys. Rev. B 78, 033307 (2008)] published Wed Jul 23, 2008.
The local electronic structure of alpha -Li[sub 3]N
T. T. Fister, G. T. Seidler, E. L. Shirley, F. D. Vila, J. J. Rehr et al.
New theoretical and experimental investigations of the occupied and unoccupied local electronic densities of states (DOS) are reported for alpha-LiN. Band-structure and density-functional theory calculations confirm the absence of covalent bonding character. However, real-space full-multiple-scatter ... [J. Chem. Phys. 129, 044702 (2008)] published Wed Jul 23, 2008.
On the mechanism of charge transport in pentacene
H. A. v. Laarhoven, C. F. J. Flipse, M. Koeberg, M. Bonn, E. Hendry et al.
Terahertz transient conductivity measurements are performed on pentacene single crystals, which directly demonstrate a strong coupling of charge carriers to low frequency molecular motions with energies centered around 1.1 THz. We present evidence that the strong coupling to low frequency motions is ... [J. Chem. Phys. 129, 044704 (2008)] published Wed Jul 23, 2008.
Surface states and topological invariants in three-dimensional topological insulators: Application to Bi[sub 1 - x]Sb[sub x]
Jeffrey C. Y. Teo, Liang Fu, and C. L. Kane
We study the electronic surface states of the semiconducting alloy bismuth antimony (BiSb). Using a phenomenological tight-binding model, we show that the Fermi surface for the 111 surface states encloses an odd number of time-reversal-invariant momenta (TRIM) in the surface Brillouin zone. This con ... [Phys. Rev. B 78, 045426 (2008)] published Wed Jul 23, 2008.
Density Inhomogeneity Driven Percolation Metal-Insulator Transition and Dimensional Crossover in Graphene Nanoribbons
S. Adam, S. Cho, M. S. Fuhrer, and S. Das Sarma
Transport in graphene nanoribbons with an energy gap in the spectrum is considered in the presence of random charged impurity centers. At low carrier density, we predict and establish that the system exhibits a density inhomogeneity driven two dimensional metal-insulator transition that is in the pe ... [Phys. Rev. Lett. 101, 046404 (2008)] published Wed Jul 23, 2008.
Transition-Metal-Substituted Indium Thiospinels as Novel Intermediate-Band Materials: Prediction and Understanding of Their Electronic Properties
P. Palacios, I. Aguilera, K. Sanchez, J. C. Conesa, and P. Wahnon
Results of density-functional calculations for indium thiospinel semiconductors substituted at octahedral sites with isolated transition metals (M=Ti,V) show an isolated partially filled narrow band containing three t-type states per M atom inside the usual semiconductor band gap. Thanks to this ele ... [Phys. Rev. Lett. 101, 046403 (2008)] published Wed Jul 23, 2008.
Three-dimensional numerical modeling of photonic integration with dielectric-loaded SPP waveguides
A. V. Krasavin and A. V. Zayats
Using full three-dimensional numerical modeling, we demonstrate highly efficient passive and active photonic circuit elements based on dielectric-loaded surface plasmon polariton waveguides (DLSPPWs). Highly confined surface plasmon polariton (SPP) mode having subwavelength cross section allows high ... [Phys. Rev. B 78, 045425 (2008)] published Tue Jul 22, 2008.
Effect of quantum confinement of surface electrons on an atomic motion on nanoislands: Ab initio calculations and kinetic Monte Carlo simulations
A. S. Smirnov, N. N. Negulyaev, L. Niebergall, W. Hergert, A. M. Saletsky et al.
Ab initio calculations and kinetic Monte Carlo simulations demonstrate that the quantum confinement of surface electrons to nanoislands can significantly affect the growth process at low temperatures. Formation of empty zones and orbits of an adatom motion is demonstrated for Cu nanoislands on Cu(11 ... [Phys. Rev. B 78, 041405 (2008)] published Tue Jul 22, 2008.
Detecting terahertz current fluctuations in a quantum point contact using a nanowire quantum dot
S. Gustavsson, I. Shorubalko, R. Leturcq, T. Ihn, K. Ensslin et al.
We use a nanowire quantum dot to probe high-frequency current fluctuations in a nearby quantum point contact. The fluctuations drive charge transitions in the quantum dot, which are measured in real-time with single-electron detection techniques. The quantum point contact (GaAs) and the quantum dot ... [Phys. Rev. B 78, 035324 (2008)] published Tue Jul 22, 2008.
Microcavity polaritons in disordered exciton lattices
Michal Grochol and Carlo Piermarocchi
We investigate the interaction of excitons in a two-dimensional lattice and photons in a planar cavity in the presence of disorder. The strong exciton-photon coupling is described in terms of polariton quasiparticles, which are scattered by a disorder potential. We consider three kinds of disorder: ... [Phys. Rev. B 78, 035323 (2008)] published Tue Jul 22, 2008.
Quantum molecular dynamics simulations of uranium at high pressure and temperature
Randolph Q. Hood, L. H. Yang, and John A. Moriarty
Constant-volume quantum molecular dynamics (QMD) simulations of uranium (U) have been carried out over a range of pressures and temperatures that span the experimentally observed solid orthorhombic alpha-U, body-centered-cubic (bcc), and liquid phases, using an ab initio plane-wave pseudopotential m ... [Phys. Rev. B 78, 024116 (2008)] published Tue Jul 22, 2008.
Spin-polarized electron transport in fractal semiconductor multilayers with two ferromagnetic contacts
De Liu and Xiao-Jun Kong
We investigate theoretically the transmission properties of electrons tunneling through fractal semiconductor multilayers (FSMs) sandwiched between two ferromagnets (Fs) in the presence of a spin-orbit interaction. Calculations are carried out with and without presumed randomly distributed uncertain ... [J. Appl. Phys. 104, 023707 (2008)] published Tue Jul 22, 2008.
Erratum: Grain boundary states and varistor behavior in silicon bicrystals
C. H. Seager and G. E. Pike
... [Appl. Phys. Lett. 37, 251 (2008)] published Tue Jul 22, 2008.
A new mechanism for high-frequency rectification at low temperatures in point contacts between identical metals
R. W. van der Heijden, A. G. M. Jansen, J. H. M. Stoelinga, H. M. Swartjes, and P. Wyder
Experimental results are reported of high-frequency (~ THz) radiation detection by metal-metal point contacts at low temperatures as a function of bias voltage. The dominant detection mechanism can be attributed to rectification due to electron-phonon-scattering-induced nonlinearity of the I-V chara ... [Appl. Phys. Lett. 37, 245 (2008)] published Tue Jul 22, 2008.
Time-resolved measurement of the electron-spin relaxation kinetics in GaAs
R. J. Seymour and R. R. Alfano
The spin relaxation and recombination kinetics in GaAs have been directly observed by time-resolved luminescence measurements. The spin relaxation time and initial spin alignment are separately determined in these measurements. ... [Appl. Phys. Lett. 37, 231 (2008)] published Tue Jul 22, 2008.
Surface depletion and inversion in semiconductors with arbitrary dopant profiles
D. J. Bartelink
A general analytical description of the depletion-layer problem in nonuniformly doped semiconductors is a valuable tool because it permits analytical manipulation of critical quantities for the purpose of establishing criteria and relating measurable quantities. A formulation is presented here which ... [Appl. Phys. Lett. 37, 220 (2008)] published Tue Jul 22, 2008.
Preparation of conducting and transparent thin films of tin-doped indium oxide by magnetron sputtering
M. Buchanan, J. B. Webb, and D. F. Williams
High-quality 800-A-thick films of tin-doped indium oxide have been prepared by magnetron sputtering. It is shown that films with low resistivity (~4 x 10 Omega cm) and high optical transmission (>~85% between 4000 and 8000 A) can be prepared on low-temperature (40180 degrees C) substrates with O pa ... [Appl. Phys. Lett. 37, 213 (2008)] published Tue Jul 22, 2008.
Light-induced effects in Schottky diodes on hydrogenated amorphous silicon
D. Jousse, R. Basset, S. Delionibus, and B. Bourdon
An exposure of Schottky diodes on hydrogenated amorphous silicon (a-SiH) for several hours to light (AM1) reduces by a factor of 4 the dark forward current at V=1 V as well as the photocurrent under low illumination. Annealing above 150 degrees C partly reverses the process. Current-voltage measure ... [Appl. Phys. Lett. 37, 208 (2008)] published Tue Jul 22, 2008.
Near-band-gap photoluminescence of Hg[sub 1 - x]Cd[sub x]Te
A. T. Hunter, D. L. Smith, and T. C. McGill
The results of photoluminescence studies of HgCdTe with x=0.32 and 0.48 for temperatures between 5 and 30 K are described. In the x=0.32 and x=0.48 material, band-to-band, band-to-acceptor, and donor-to-acceptor luminescence lines are observed. We report the first observation of bound-exciton lumine ... [Appl. Phys. Lett. 37, 200 (2008)] published Tue Jul 22, 2008.
Cadmium--tin-oxide films deposited by dc reactive sputtering from a Cd-Sn alloy target
N. Miyata, K. Miyake, and Y. Yamaguchi
Cadmiumtin-oxide films with high conductivity and high visible transmission were prepared by dc reactive sputtering from a Cd-Sn alloy target in an Ar-O atmosphere. The electrical and optical properties of these films were found to depend strongly uponthe oxygen concentration in an Ar-O atmosphere d ... [Appl. Phys. Lett. 37, 180 (2008)] published Tue Jul 22, 2008.
Cyclotron resonance and the magnetophonon effect in Ga[sub x]In[sub 1 - x]As[sub y]P[sub 1 - y]
R. J. Nicholas, S. J. Sessions, and J. C. Portal
Cyclotron resonance and the magnetophonon effect have been used to measure the effective mass as a function of alloy composition for GaInAsP samples grown lattice matched to InP. Values of omegatau of up to 6 allow an accurate measurement of effective mass, which is found to depend linearly upon all ... [Appl. Phys. Lett. 37, 178 (2008)] published Tue Jul 22, 2008.
Dependence of the electrical characteristics of heavily Ge-doped GaAs on molecular beam epitaxy growth parameters
G. M. Metze, R. A. Stall, C. E. C. Wood, and L. F. Eastman
Ge incorporation into molecular beam epitaxial GaAs as a function of substrate temperature (350620 degrees C), Ge flux (1010 cm sec) and of As/Ga flux ratio (10/1) has been studied. The free-electron (7.4 x 10 cm) and free-hole (3.0 x 10 cm) concentrations in GaAs were the highest obtained to date. ... [Appl. Phys. Lett. 37, 165 (2008)] published Tue Jul 22, 2008.
Computer controlled apparatus for measuring contact electrification of polymers
Manfred Hennecke
An on-line computer controlled apparatus for measuring the contact electrification of polymers due to subsequent intermittent contacts is developed. The utilization of measuring probes and metal contact pins instead of the plotter pens of a programmable four-colour plotter renders it possible to sim ... [Rev. Sci. Instrum. 51, 803 (2008)] published Tue Jul 22, 2008.
Comparison of multiple-scan direct and lock-in detection in magnetic resonance: Application to nuclear acoustic resonance
G. R. Ashton, D. K. Hsu, and R. G. Leisure
Theoretical expressions are derived for the signal-to-noise ratios in magnetic resonance experiments for the lock-in and multiple-scan direct detection schemes. Effects of noise character, post-spectrometer filters, and modulation frequency are included in the analysis. The theoretical results are f ... [Rev. Sci. Instrum. 51, 454 (2008)] published Tue Jul 22, 2008.
Stroboscopic Wave-Packet Description of Nonequilibrium Many-Electron Problems
P. Bokes, F. Corsetti, and R. W. Godby
We introduce the construction of an orthogonal wave-packet basis set, using the concept of stroboscopic time propagation, tailored to the efficient description of nonequilibrium extended electronic systems. Thanks to three desirable properties of this basis, significant insight is provided into none ... [Phys. Rev. Lett. 101, 046402 (2008)] published Tue Jul 22, 2008.
Origin of high mobility within an amorphous polymeric semiconductor: Space-charge-limited current and trap distribution
Dae Sung Chung, Dong Hoon Lee, Chanwoo Yang, Kipyo Hong, Chan Eon Park et al.
To elucidate the origin of the high field-effect mobility ([approximate]0.02 cm/V s) of amorphous poly[(1,2-bis-(2-thienyl)vinyl-5,5-diyl)-alt-(9,9-dioctyldecylfluorene-2,7-diyl], we investigated the current densityvoltage (J-V) and mobilityvoltage ([mu]-V) relationships as a function of temperatu ... [Appl. Phys. Lett. 93, 033303 (2008)] published Tue Jul 22, 2008.
Atomistic simulation on charge mobility of amorphous tris(8-hydroxyquinoline) aluminum (Alq[sub 3]): Origin of Poole--Frenkel--type behavior
Yuki Nagata and Christian Lennartz
The atomistic simulation of charge transfer process for an amorphous Alq system is reported. By employing electrostatic potential charges, we calculate site energies and find that the standard deviation of site energy distribution is about twice as large as predicted in previous research. The charge ... [J. Chem. Phys. 129, 034709 (2008)] published Mon Jul 21, 2008.
Single switch surface hopping for a model of pyrazine
Caroline Lasser and Torben Swart
The single switch trajectory surface hopping algorithm is tested for numerical simulations of a two-state three-mode model for the internal conversion of pyrazine through a conical intersection of potential energy surfaces. The algorithm is compared to two other surface hopping approaches, namely, T ... [J. Chem. Phys. 129, 034302 (2008)] published Mon Jul 21, 2008.
Electron Land[e-acute] g factor in GaAs--(Ga,Al)As quantum wells under applied magnetic fields: Effects of Dresselhaus spin splitting
E. Reyes-Gomez, N. Porras-Montenegro, C. A. Perdomo-Leiva, H. S. Brandi, and L. E. Oliveira
The effects of the Dresselhaus spin splitting on the Lande g factor associated with conduction electrons in GaAs(Ga,Al)As quantum wells are studied by using the nonparabolic OggMcCombe effective Hamiltonian. The g factor and cyclotron effective mass are calculated as functions of applied magnetic fi ... [J. Appl. Phys. 104, 023704 (2008)] published Mon Jul 21, 2008.
Study of metal-related deep-level defects in germanide Schottky barriers on n-type germanium
E. Simoen, K. Opsomer, C. Claeys, K. Maex, C. Detavernier et al.
Deep levels have been studied in n-type germanium subjected to Co, Fe, Cu, Cr, and Pt germanidation in the temperature range between 300 and 700 degrees C by deep-level transient spectroscopy (DLTS). It is shown that most DLTS peaks can be assigned to acceptor levels of substitutional metal atoms. ... [J. Appl. Phys. 104, 023705 (2008)] published Mon Jul 21, 2008.
Reverse-magnetic-field reciprocity in conductive samples with extended contacts
Martin Cornils and Oliver Paul
This paper reports on the extension of the reverse-magnetic-field reciprocity (RMFR) principle to electrically linear devices with arbitrary shape and extended contacts. The RMFR principle is a consequence of Onsager's relation for the conductivity tensor depending on the magnetic field. It states t ... [J. Appl. Phys. 104, 024505 (2008)] published Mon Jul 21, 2008.
Band structures of GaAs, InAs, and InP: A 34 [bold k] [center-dot] [bold p] model
I. Saidi, S. Ben Radhia, and K. Boujdaria
The band structure of direct-band gap semiconductors (GaAs, InAs, InP) is described theoretically by using a 34 x 34 kp model. We extend the spd basis functions by the inclusion of s orbitals. We find that the spds kp model is sufficient to describe the electronic structure of all materials investig ... [J. Appl. Phys. 104, 023706 (2008)] published Mon Jul 21, 2008.
First-principles study of edge chemical modifications in graphene nanodots
Huaixiu Zheng and Walter Duley
Rectangular graphene nanodots have both armchair and zigzag edges, which can be terminated with a variety of atoms or molecular groups. Our first-principles study shows that edge chemical modification can alter the electronic structure of graphene nanodots significantly. We find that when saturated ... [Phys. Rev. B 78, 045421 (2008)] published Mon Jul 21, 2008.
Modeling electron-spin accumulation in a metallic nanoparticle
Y. G. Wei, C. E. Malec, and D. Davidovic
A model describing spin-polarized current via discrete energy levels of a metallic nanoparticle, which has strongly asymmetric tunnel contacts to two ferromagnetic leads, is presented. In absence of spin relaxation, the model leads to a spin accumulation in the nanoparticle, a difference (Delta[mu]) ... [Phys. Rev. B 78, 035435 (2008)] published Mon Jul 21, 2008.
Mode locking and mode competition in a nonequilibrium solid-state condensate
P. R. Eastham
A trapped polariton condensate with continuous pumping and decay is analyzed using a generalized GrossPitaevskii model. Whereas an equilibrium condensate is characterized by a macroscopic occupation of a ground state, here the steady states take more general forms. Some are characterized by a large ... [Phys. Rev. B 78, 035319 (2008)] published Mon Jul 21, 2008.
Ultrafast electron dynamics in Pb/Si(111) investigated by two-photon photoemission
Patrick S. Kirchmann and Uwe Bovensiepen
Ultrafast electron dynamics in Pb/Si(111) quantum well structures have been investigated by femtosecond time-resolved two-photon photoemission spectroscopy. Three unoccupied quantum well states (or subbands) as well as an image potential state are identified and analyzed as a function of Pb thicknes ... [Phys. Rev. B 78, 035437 (2008)] published Mon Jul 21, 2008.
Dynamics of density imbalanced bilayer holes in the quantum Hall regime
S. Misra, N. C. Bishop, E. Tutuc, and M. Shayegan
We report magnetotransport measurements on bilayer GaAs hole systems with unequal hole concentrations in the two layers. At magnetic fields where one layer is in the integer quantum Hall state and the other has bulk extended states at the Fermi energy, the longitudinal and the Hall resistances of th ... [Phys. Rev. B 78, 035322 (2008)] published Mon Jul 21, 2008.
Magnetic properties of the charge density wave compounds RTe[sub 3] (R = Y, La, Ce, Pr, Nd, Sm, Gd, Tb, Dy, Ho, Er, and Tm)
N. Ru, J.-H. Chu, and I. R. Fisher
The antiferromagnetic transition is investigated in the rare-earth (R) tritelluride RTe family of charge-density wave (CDW) compounds via specific heat, magnetization, and resistivity measurements. Observation of the opening of a superzone gap in the resistivity of DyTe indicates that additional nes ... [Phys. Rev. B 78, 012410 (2008)] published Mon Jul 21, 2008.
Reversible resistive switching behaviors in NiO nanowires
Sung In Kim, Jae Hak Lee, Young Wook Chang, Sung Sic Hwang, and Kyung-Hwa Yoo
We have investigated resistive switching phenomena in NiO nanowires fabricated using anodized aluminum oxide membranes. We show that NiO nanowires exhibit reversible and bistable resistive switching behaviors like those in NiO thin films. However, compared to NiO thin films, electroforming in NiO na ... [Appl. Phys. Lett. 93, 033503 (2008)] published Mon Jul 21, 2008.
Evolution of valence-band alignment with nitrogen content in GaNAs/GaAs single quantum wells
Jun Shao, Wei Lu, M. Sadeghi, Xiang Lu, S. M. Wang et al.
We report on experimental evidence for the transition of valence-band alignment from type I to type II in GaNAs/GaAs single quantum wells by photoreflectance measurements. The substitutional nitrogen content covers a range of 1.4%5.9%. The turning point of the type Itype II transition occurs at x>~4 ... [Appl. Phys. Lett. 93, 031904 (2008)] published Mon Jul 21, 2008.
Origin of high mobility within an amorphous polymeric semiconductor: Space-charge-limited current and trap distribution
Dae Sung Chung, Dong Hoon Lee, Chanwoo Yang, Kipyo Hong, Chan Eon Park et al.
To elucidate the origin of the high field-effect mobility ([approximate]0.02 cm/V s) of amorphous poly[(1,2-bis-(2-thienyl)vinyl-5,5-diyl)-alt-(9,9-dioctyldecylfluorene-2,7-diyl], we investigated the current densityvoltage (J-V) and mobilityvoltage ([mu]-V) relationships as a function of temperatu ... [Appl. Phys. Lett. 93, 033303 (2008)] published Mon Jul 21, 2008.
Chromium and tantalum site substitution patterns in Ni[sub 3]Al (L1[sub 2]) gamma[sup [prime]]-precipitates
Christopher Booth-Morrison, Zugang Mao, Ronald D. Noebe, and David N. Seidman
The site substitution behavior of Cr and Ta in the NiAl (L1)-type gamma-precipitates of a NiAlCrTa alloy is investigated by atom-probe tomography (APT) and first-principles calculations. Measurements of the gamma-phase composition by APT suggest that Al, Cr, and Ta share the Al sublattice sites of ... [Appl. Phys. Lett. 93, 033103 (2008)] published Mon Jul 21, 2008.
Highly Conductive Molecular Junctions Based on Direct Binding of Benzene to Platinum Electrodes
M. Kiguchi, O. Tal, S. Wohlthat, F. Pauly, M. Krieger et al.
Highly conductive molecular junctions were formed by direct binding of benzene molecules between two Pt electrodes. Measurements of conductance, isotopic shift in inelastic spectroscopy, and shot noise compared with calculations provide indications for a stable molecular junction where the benzene m ... [Phys. Rev. Lett. 101, 046801 (2008)] published Mon Jul 21, 2008.
Periodic solutions of the classical polaron and bipolaron systems
F. Peeters and J. T. Devreese
It is shown that the exact solutions for the classical polaron model derived by Evrard et al. (the electron rotates about a fixed polaron centre with frequency Omega>>omega) exist also for the discrete frequencies Omega=omega/(n+ 1/2 )(omega is the longitudinal optical phonon frequency and n is an i ... [J. Math. Phys. 21, 2302 (2008)] published Mon Jul 21, 2008.
Multipoles and excitons in higher-order coherence
Andrei N. Weiszmann
Considering the coherence properties of an inelastically scattered quantum radiation by an ensemble of N identical three level atoms in a solid-like array, we addressed the question whether this process is actually mediated by a series of multipole interactions and/or a series of virtual intermediat ... [J. Math. Phys. 21, 1546 (2008)] published Mon Jul 21, 2008.
Multigap Superconductivity in the Heavy-Fermion System CeCoIn[sub 5]
G. Seyfarth, J. P. Brison, G. Knebel, D. Aoki, G. Lapertot et al.
New thermal conductivity experiments on the heavy-fermion superconductor CeCoIn down to 10 mK rule out the suggested existence of unpaired electrons. Moreover, they reveal strong multigap effects with a remarkably low critical field H for the small gap band, showing that the complexity of heavy-ferm ... [Phys. Rev. Lett. 101, 046401 (2008)] published Mon Jul 21, 2008.
Colossal spin fluctuations in a molecular quantum dot magnet with ferromagnetic electrodes
Thibaut Jonckheere, Ken-Ichiro Imura, and Thierry Martin
We study electronic transport through a magnetic molecule with an intrinsic spin S coupled to two magnetic electrodes in the incoherent regime. The molecule is modeled as a single resonant level with large Coulomb repulsion (no double occupancy). The molecular spin is isotropic and it interacts with ... [Phys. Rev. B 78, 045316 (2008)] published Fri Jul 18, 2008.
Effect of thermal annealing on the hyperfine interaction in InAs/GaAs quantum dots
M. Yu. Petrov, I. V. Ignatiev, S. V. Poltavtsev, A. Greilich, A. Bauschulte et al.
The hyperfine interaction of an electron with the unpolarized nuclei in thermally annealed self-assembled InAs/GaAs quantum dots (QDs) is theoretically analyzed. For this purpose, the thermal annealing process of the quantum dots is numerically modeled to obtain the nuclear composition as well as th ... [Phys. Rev. B 78, 045315 (2008)] published Fri Jul 18, 2008.
Hybrid skew scattering regime of the anomalous Hall effect in Rashba systems: Unifying Keldysh, Boltzmann, and Kubo formalisms
Alexey A. Kovalev, Karel Vyborny, and Jairo Sinova
We present the analytical description of the anomalous Hall effect (AHE) in a two-dimensional electron gas (2DEG) ferromagnet within the Keldysh formalism. These results unify the three linear-response approaches to AHE and close the debate on previous discrepancies. We are able to identify a new ex ... [Phys. Rev. B 78, 041305 (2008)] published Fri Jul 18, 2008.
Dissipative two-electron transfer: A numerical renormalization group study
Sabine Tornow, Ralf Bulla, Frithjof B. Anders, and Abraham Nitzan
We investigate nonequilibrium two-electron transfer in a model redox system represented by a two-site extended Hubbard model and embedded in a dissipative environment. The influence of the electron-electron interactions and the coupling to a dissipative bosonic bath on the electron transfer is studi ... [Phys. Rev. B 78, 035434 (2008)] published Fri Jul 18, 2008.
Specific heat variation as T[sup 0.5] in Th-doped UIr[sub 2]Zn[sub 20]: Consistent with weak coupled quantum critical behavior
J. S. Kim, G. R. Stewart, and E. D. Bauer
By partially replacing the U in single crystals of UIrZn with Th, we have suppressed the 2.1 K ferromagnetic-like transition present in the pure compound. The magnetic susceptibilities of UThIrZn show enhanced low-temperature values, with chi (2 K) for x=0.25 around 140 memu/Umole. However, unlike ... [Phys. Rev. B 78, 035121 (2008)] published Fri Jul 18, 2008.
Theoretical investigation of electron transport modulation through benzenedithiol by substituent groups
Manuel Smeu, Robert A. Wolkow, and Gino A. DiLabio
Density functional theory combined with nonequilibrium Green's function techniques was used to model the conduction through disubstituted benzenedithiol molecules bonded to leads composed of 3 x 3, 5 x 5 gold and 3 x 3 aluminum. For the disubstituted 3 x 3 Au-benzenedithiol-Au systems, the small lea ... [J. Chem. Phys. 129, 034707 (2008)] published Fri Jul 18, 2008.
Improvement of Characteristics of Ga-Doped ZnO Grown by Pulsed Laser Deposition Using Plasma-Enhanced Oxygen Radicals
Min-Suk Oh, Dae-Kue Hwang, Dong-Jun Seong, Hyun-Sang Hwang, Seong-Ju Park et al.
The authors report on the growth and characterization of Ga-doped ZnO films grown at a low temperature (100 degrees C) by oxygen plasma-enhanced pulsed laser deposition (PE-PLD). The introduction of oxygen radicals during PLD growth remarkably improved the crystalline quality, surface morphology, an ... [J. Electrochem. Soc. 155, D599 (2008)] published Fri Jul 18, 2008.
Ballistic hot electron transport in graphene
Wang-Kong Tse, E. H. Hwang, and S. Das Sarma
We theoretically study the inelastic scattering rate and the carrier mean free path for energetic hot electrons in graphene, including both electron-electron and electron-phonon interactions. Taking account of optical phonon emission and electron-electron scattering, we find that the inelastic scatt ... [Appl. Phys. Lett. 93, 023128 (2008)] published Fri Jul 18, 2008.
One-Dimensional 3d Electronic Bands of Monatomic Cu Chains
P. H. Zhou, P. Moras, L. Ferrari, G . Bihlmayer, S. Blugel et al.
The electronic structure of an array of monatomic Cu chains grown on the Pt(997) surface has been examined by angle-resolved photoemission. The monatomic wires exhibit properties associated with 3d electron confinement in one dimension. Along the wire direction, the 3d bands states display a dispers ... [Phys. Rev. Lett. 101, 036807 (2008)] published Fri Jul 18, 2008.
Charge Transport in Chemically Doped 2D Graphene
Aurelien Lherbier, X. Blase, Yann-Michel Niquet, Francois Triozon, and Stephan Roche
We report on a numerical study of electronic transport in chemically doped 2D graphene materials. By using ab initio calculations, a self-consistent scattering potential is derived for boron and nitrogen substitutions, and a fully quantum-mechanical Kubo-Greenwood approach is used to evaluate the re ... [Phys. Rev. Lett. 101, 036808 (2008)] published Fri Jul 18, 2008.
Tailoring Exchange Interactions in Engineered Nanostructures: An Ab Initio Study
O. O. Brovko, P. A. Ignatiev, V. S. Stepanyuk, and P. Bruno
We present a novel approach to spin manipulation in atomic-scale nanostructures. Our ab initio calculations clearly demonstrate that it is possible to tune magnetic properties of subnanometer structures by adjusting the geometry of the system. By the example of two surface-based systems we demonstra ... [Phys. Rev. Lett. 101, 036809 (2008)] published Fri Jul 18, 2008.
Electric Manipulation of Spin Relaxation Using the Spin Hall Effect
K. Ando, S. Takahashi, K. Harii, K. Sasage, J. Ieda et al.
Using the spin Hall effect, magnetization relaxation in a NiFe/Pt film is manipulated electrically. An electric current applied to the Pt layer exerts spin torque on the entire magnetization of the NiFe layer via the macroscopic spin transfer induced by the spin Hall effect and modulates the magneti ... [Phys. Rev. Lett. 101, 036601 (2008)] published Fri Jul 18, 2008.
Complex Quasiparticle Band Structure Induced by Electron-Phonon Interaction: Band Splitting in the 1 x 1H/W(110) Surface
Asier Eiguren and Claudia Ambrosch-Draxl
We show that the self-consistent solution of the complex Dyson equation for the electron-phonon (EP) problem introduces many body effects which are often observed in photoemission experiments. The formalism is applied to the H covered W(110) surface, using first-principles results for the electronic ... [Phys. Rev. Lett. 101, 036402 (2008)] published Fri Jul 18, 2008.
Publisher's Note: Localized Magnetic States in Graphene [Phys. Rev. Lett. [bold 101], 026805 (2008)]
Bruno Uchoa, Valeri N. Kotov, N. M. R. Peres, and A. H. Castro Neto
... [Phys. Rev. Lett. 101, 039903 (2008)] published Fri Jul 18, 2008.
Non-Bloch Nature of Alloy States in a Conventional Semiconductor Alloy: Ga[sub x]In[sub 1-x]P as an Example
Yong Zhang, A. Mascarenhas, and L.-W. Wang
Using GaInP as a prototype system, we present the first systematic examination of the alloy scattering effects on the global electronic structure of a semiconductor alloy for the whole composition range. Contrary to conventional wisdom, many electronic states in such a well behaved alloy are found t ... [Phys. Rev. Lett. 101, 036403 (2008)] published Fri Jul 18, 2008.
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.
Geometry and electronic stability of tungsten encapsulated silicon nanotubes
Qi Peng, Jiang Shen, and Nan-Xian Chen
Density functional theory involving generalized gradient approximation (both PW91 and BLYP level calculations are considered and compared) correlation functional is used to investigate the stability of W encapsulated W@Si (n=16) hexagonal prism (HP) nanotubes and W@Si (n=16) AB type nanotubes. We fo ... [J. Chem. Phys. 129, 034704 (2008)] published Thu Jul 17, 2008.
On the role of the nonlocal Hartree--Fock exchange in ab initio quantum transport: H[sub 2] in Pt nanocontacts revisited
Y. Garcia and J. C. Sancho-Garcia
We propose a practical way to overcome the ubiquitous problem of the overestimation of the zero-bias and zero-temperature conductance, which is associated with the use of local approximations to the exchange-correlation functional in density-functional theory when applied to quantum transport. This ... [J. Chem. Phys. 129, 034702 (2008)] published Thu Jul 17, 2008.
Mesoscopic simulation of entanglements using dissipative particle dynamics: Application to polymer brushes
Florent Goujon, Patrice Malfreyt, and Dominic J. Tildesley
We use a simple spring-spring repulsion to model entanglements between polymers in dissipative particle dynamics (DPD) simulations. The model is applied to a polymer brushes system to study lubrication. We demonstrate that this method leads to mechanical equilibrium in polymer brushes using the norm ... [J. Chem. Phys. 129, 034902 (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.
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.
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.
Application of block diagonal technique to Hamiltonian matrix in performing spin-splitting calculations for GaAs zincblende bulk and quantum wells
Chun-Nan Chen, Wei-Long Su, Kuo-Ching Chang, Sheng-Hsiung Chang, Jih-Chen Chiang et al.
The 2 x 2 conduction band, 4 x 4 hole band, and 2 x 2 spin-orbit split-off band matrices of zincblende semiconductors are obtained by using a block diagonal technique. Importantly, the block diagonal matrices incorporate not only the interband coupling effect but also the bulk inversion asymmetry ef ... [J. Appl. Phys. 104, 024901 (2008)] published Thu Jul 17, 2008.
Electronic transport in heavily Si doped cubic boron nitride films epitaxially grown on diamond(001)
Hong Yin, Ivan Pongrac, and Paul Ziemann
Structural phase analysis and measurements of electronic transport properties were carried out on heavily Si-implanted cubic (c-) BN films heteroepitaxially grown on diamond(001). Pure cubic phase can be conserved after Si implantation up to a concentration of 2 x 10 cm and a related implantation d ... [J. Appl. Phys. 104, 023703 (2008)] published Thu Jul 17, 2008.
Interaction-Induced Harmonic Frequency Mixing in Quantum Dots
M. Thorwart, R. Egger, and A. O. Gogolin
We show that harmonic frequency mixing in quantum dots coupled to two leads under the influence of time-dependent voltages of different frequency is dominated by interaction effects. This offers a unique and direct spectroscopic tool to access correlations, and holds promise for efficient frequency ... [Phys. Rev. Lett. 101, 036806 (2008)] published Thu Jul 17, 2008.