publicationDate stringlengths 1 2.79k | title stringlengths 1 36.5k ⌀ | abstract stringlengths 1 37.3k ⌀ | id stringlengths 9 47 |
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2003-03-07 | Vortex phase diagram in rotating two-component Bose-Einstein condensates | We investigate the structure of vortex states in rotating two-component
Bose-Einstein condensates with equal intracomponent but varying intercomponent
coupling constants. A phase diagram in the intercomponent-coupling versus
rotation-frequency plane reveals rich equilibrium structures of vortex states.
As the ratio of ... | 0303125v3 |
2003-03-09 | Relevance of many-body interactions for correlated electrons in the strong-coupling limit | Many-body interactions in effective field theories for disordered interacting
electrons are considered. It is shown that three-body and higher interaction
terms are generated in perturbation theory, and some of the physical
consequences of these interactions are discussed. It is shown in particular
that they will in ge... | 0303151v1 |
2003-04-11 | Coupled plasmon-phonon modes in a two-dimensional electron gas in the presence of Rashba effect | Elementary electronic excitation is studied theoretically for a 2DEG in the
presence of spin orbit (SO) interaction induced by Rashba effect. In such a
system, coupled plasmon-phonon excitation can be achieved via intra- and
inter-SO electronic transitions. As a result, six branches of the coupled
plasmon-phonon oscill... | 0304257v1 |
2003-05-13 | Transition between Quantum States in a Parallel-Coupled Double-Quantum-Dot | Strong electron and spin correlations in a double-quantum-dot (DQD) can give
rise to different quantum states. We observe a continuous transition from a
Kondo state exhibiting a single-peak Kondo resonance to another exhibiting a
double peak by increasing the inter-dot-coupling (t) in a parallel-coupled DQD.
The transi... | 0305289v1 |
2003-05-16 | Correlation Functions of the Magnetization in Thin Films | We calculate the correlation functions of uniform magnetization in thin
ferromagnetic films for small deviations from equilibrium, by using a
functional formalism. To take account of dissipation and fluctuations
consistently, the magnetization is coupled to a bosonic heat bath. The
correlation functions show strong dep... | 0305400v1 |
2003-05-19 | Spin-phonon interaction and band effects in the high-T_C superconductor HgBa_2CuO_4 | Band calculations show that a stripe-like anti-ferromagnetic spin wave is
enforced by a 'half-breathing' phonon distortion within the CuO plane of
HgBa_2CuO_4. This spin-phonon coupling is increased further by shear distortion
and by increased distance between Cu and apical oxygens. The effects from
spin-phonon couplin... | 0305438v1 |
2003-05-30 | Mesoscopic effects in adiabatic spin pumping | We show that temporal shape modulations (pumping) of a quantum dot in the
presence of spin-orbital coupling lead to a finite dc spin current. Depending
on the strength of the spin-orbit coupling, the spin current is polarized
perpendicular to the plane of the two-dimensional electron gas, or has an
arbitrary direction ... | 0306001v2 |
2003-06-04 | Vibration Mode Induced Shapiro Steps and Backaction in Josephson Junctions | A model of a superconducting tunnel junction coupled to a mechanical
oscillator is studied at zero temperature in the case of linear coupling
between the oscillator and tunneling electrons. It is found that the Josephson
current flowing between two superconductors is modulated by the motion of the
oscillator. Coupling ... | 0306107v2 |
2003-06-10 | Correlation functions for 1d interacting fermions with spin-orbit coupling | We compute correlation functions for one-dimensional electron systems which
spin and charge degrees of freedom are coupled through spin-orbit coupling.
Charge density waves, spin density waves, singlet- triplet- superconducting
fluctuations are studied. We show that the spin-orbit interaction modify the
exponents and t... | 0306251v1 |
2003-06-26 | Quantum tunneling in a three dimensional network of exchange coupled single-molecule magnets | A Mn4 single-molecule magnet (SMM) is used to show that quantum tunneling of
magnetization (QTM) is not suppressed by moderate three dimensional exchange
coupling between molecules. Instead, it leads to an exchange bias of the
quantum resonances which allows precise measurements of the effective exchange
coupling that ... | 0306669v1 |
2003-07-01 | Spin clustering and ferromagnetic couplings in a dilute magnetic semiconductor | Ferromagnetic couplings in spin clusters are shown to be strongly enhanced
compared to those for an ordered impurity arrangement, even for the same spin
separation and hole doping. The consequent energy-enhancement of the
cluster-localized spin-wave modes indicates a potentially significant role of
positional Mn disord... | 0307009v1 |
2003-08-06 | Unexpected non-Wigner behavior in level-spacing distributions of next-nearest-neighbor coupled XXZ spin chains | The level-spacing distributions of XXZ spin chains with next-nearest-neighbor
couplings are studied under periodic boundary conditions. We confirm that
integrable XXZ spin chains mostly have the Poisson distribution as expected. On
the contrary, the level-spacing distributions of next-nearest-neighbor coupled
XXZ chain... | 0308099v1 |
2003-08-08 | Dynamics of Ising models coupled microscopically to bath systems | Based on the Robertson theory the nonlinear dynamics of general Ising systems
coupled microscopically to bath systems is investigated leading to two
complimentary approaches. Within the master equation approach microscopically
founded transition rates are presented which essentially differ from the usual
phenological r... | 0308172v1 |
2003-09-02 | Interlayer Exchange Coupling in (MnTe)_m (ZnTe)_n Superlattices | The interlayer exchange coupling mediated by the valence band electrons in
$\textrm{(MnTe)}_{\textrm{m}} \textrm{(ZnTe)}_{\textrm{n}}$ superlattices has
been examined theoretically. The calculations have been performed within the
framework of three dimensional tight binding model. Both types of magnetic
configurations ... | 0309063v1 |
2003-09-30 | Coulomb effects in tunneling through a quantum dot stack | Tunneling through two vertically coupled quantum dots is studied by means of
a Pauli master equation model. The observation of double peaks in the
current-voltage characteristic in a recent experiment is analyzed in terms of
the tunnel coupling between the quantum dots and the coupling to the contacts.
Different regime... | 0309696v1 |
2003-10-06 | Spin Current in Spin-Orbit Coupling Systems | We present a simple and pedagogical derivation of the spin current as the
linear response to an external electric field for both Rashba and Luttinger
spin-orbital coupling Hamiltonians. Except for the adiabatic approximation, our
derivation is exact to the linear order of the electric field for both models.
The spin cu... | 0310093v2 |
2003-10-06 | Electron-phonon coupling and its evidence in the photoemission spectra of lead | We present a detailed study on the influence of strong electron-phonon
coupling to the photoemission spectra of lead. Representing the strong-coupling
regime of superconductivity, the spectra of lead show characteristic features
that demonstrate the correspondence of physical properties in the normal and
the supercondu... | 0310119v1 |
2003-10-30 | Transport through multiply connected quantum wires | We study transport through multiply coupled carbon nano-tubes (quantum wires)
and compute the conductances through the two wires as a function of the two
gate voltages $g_1$ and $g_2$ controlling the chemical potential of the
electrons in the two wires. We find that there is an {\it equilibrium}
cross-conductance, and ... | 0310713v1 |
2003-11-03 | Cascade of Quantum Phase Transitions in Tunnel-Coupled Edge States | We report on the cascade of quantum phase transitions exhibited by
tunnel-coupled edge states across a quantum Hall line junction. We identify a
series of quantum critical points between successive strong and weak tunneling
regimes in the zero-bias conductance. Scaling analysis shows that the
conductance near the criti... | 0311022v2 |
2003-11-04 | Twisted exchange interaction between localized spins embedded in a one- or two-dimensional electron gas with Rashba spin-orbit coupling | We study theoretically the Ruderman-Kittel-Kasuya-Yosida (RKKY) interaction
in one- and two-dimensions in presence of a Rashba spin-orbit (SO) coupling. We
show that rotation of the spin of conduction electrons due to SO coupling
causes a twisted RKKY interaction between localized spins which consists of
three differen... | 0311054v1 |
2003-11-05 | Charge density plateaux and insulating phases in the $t-J$ model with ladder geometry | We discuss the occurrence and the stability of charge density plateaux in
ladder-like $t-J$ systems (at zero magnetization M=0) for the cases of 2- and
3-leg ladders. Starting from isolated rungs at zero leg coupling, we study the
behaviour of plateaux-related phase transitions by means of first order
perturbation theo... | 0311107v1 |
2003-11-18 | Pairing fluctuation effects on the single-particle spectra for the superconducting state | Single-particle spectra are calculated in the superconducting state for a
fermionic system with an attractive interaction, as functions of temperature
and coupling strength from weak to strong. The fermionic system is described by
a single-particle self-energy that includes pairing-fluctuation effects in the
supercondu... | 0311424v1 |
2003-12-11 | Kondo Effect and Josephson Current through a Quantum Dot between Two Superconductors | We investigate the supercurrent through a quantum dot for the whole range of
couplings using the numerical renormalization group method. We find that the
Josephson current switches abruptly from a $\pi$- to a 0-phase as the coupling
increases. At intermediate couplings the total spin in the ground state depends
on the ... | 0312271v2 |
2004-01-07 | Spin-triplet s-wave local pairing induced by Hund's rule coupling | We show within the dynamical mean field theory that local multiplet
interactions such as Hund's rule coupling produce local pairing
superconductivity in the strongly correlated regime. Spin-triplet
superconductivity driven by the Hund's rule coupling emerges from the pairing
mediated by local fluctuations in pair excha... | 0401104v1 |
2004-01-16 | Magnetic field induced phase transitions in spin ladders with ferromagnetic legs | We study the phase diagram of spin ladders with ferromagnetic legs under the
influence of a symmetry breaking magnetic field in the weak coupling effective
field theory by bosonization. For antiferromagnetic interleg coupling we
identify two phase transitions introduced by the external magnetic field. In
order to estab... | 0401301v1 |
2004-01-29 | Bose-representation for a strongly coupled nonequilibrim fermionic superfluid in a time-dependent trap | Using the functional integral formulation of a nonequilibrium quantum
many-body theory we develop a regular description of a Fermi system with a
strong attractive interaction in the presence of an external time-dependent
potential. In the strong coupling limit this fermionic system is equivalent to
a noequilibrium dilu... | 0401603v1 |
2004-01-30 | Superconductivity Driven by Chain Coupling and Electronic Correlations | We present an analysis of a system of weakly coupled Hubbard chains based on
combining an exact study of spectral functions of the uncoupled chain system
with a renormalization group method for the coupled chains. For low values of
the onsite repulsion $U$ and of the doping $\delta$, the leading instability is
towards ... | 0401642v2 |
2004-02-02 | Quantum theory of a vortex line in an optical lattice | We investigate the quantum theory of a vortex line in a stack of
weakly-coupled two-dimensional Bose-Einstein condensates, that is created by a
one-dimensional optical lattice. We derive the dispersion relation of the
Kelvin modes of the vortex line and also study the coupling between the Kelvin
modes and the quadrupol... | 0402052v2 |
2004-02-03 | The Fermi Surface Effect on Magnetic Interlayer Coupling | The oscillating magnetic interlayer coupling of Fe over spacer layers
consisting of Cu$_{x}$Pd$_{1-x}$ alloys is investigated by first principles
density functional theory. The amplitude, period and phase of the coupling, as
well as the disorder-induced decay, are analyzed in detail and the consistency
to the Ruderman-... | 0402093v1 |
2004-02-09 | Phase diagram and critical exponents of a dissipative Ising spin chain in a transverse magnetic field | We consider a one-dimensional Ising model in a transverse magnetic field
coupled to a dissipative heat bath. The phase diagram and the critical
exponents are determined from extensive Monte Carlo simulations. It is shown
that the character of the quantum phase transition is radically altered from
the corresponding non-... | 0402224v2 |
2004-02-13 | Quantum dynamics of two capacitively coupled superconducting islands via Josephson junctions | In this paper, we consider a system consisting of two capacitively coupled
superconducting islands via Josephson junctions. We show that it can be reduced
to two coupling harmonic oscillators under certain conditions, and solved
exactly in terms of a displacing transformation, a beam-splitter-like
transformation, and a... | 0402354v1 |
2004-02-28 | Resonant Spin Hall Conductance in Two-Dimensional Electron Systems with Rashba Interaction in a Perpendicular Magnetic Field | We study transport properties of a two-dimensional electron system with
Rashba spin-orbit coupling in a perpendicular magnetic field. The spin orbit
coupling competes with Zeeman splitting to introduce additional degeneracies
between different Landau levels at certain magnetic fields. This degeneracy, if
occuring at th... | 0403005v1 |
2004-03-01 | Raman scattering on phonon-plasmon coupled modes in magnetic fields | Raman scattering on phonon--plasmon coupled modes in high magnetic fields is
considered theoretically. The calculations of the dielectric function were
performed in the long-wave approximation for the semiclassical and
ultra-quantum magnetic fields taking into account the electron damping and
intrinsic lifetime of opti... | 0403044v1 |
2004-03-02 | Dynamical systems with time-dependent coupling: Clustering and critical behaviour | We study the collective behaviour of an ensemble of coupled motile elements
whose interactions depend on time and are alternatively attractive or
repulsive. The evolution of interactions is driven by individual internal
variables with autonomous dynamics. The system exhibits different dynamical
regimes, with various fo... | 0403081v1 |
2004-03-06 | Luttinger liquid with strong spin-orbital coupling and Zeeman splitting in quantum wires | We study a one-dimensional interacting electron gas with the strong Rashba
spin-orbit coupling and Zeeman splitting in a quantum well. A bosonization
theory is developed for this system. The tunneling current may deviate from a
simple power law which is that in an ordinary Luttinger liquid. The microscopic
interacting ... | 0403183v1 |
2004-03-29 | Ground state, electronic structure and magnetism of LaMnO3 | We have calculated the discrete low-energy electronic structure in LaMnO3
originating from the atomic-like states of the strongly correlated 3d4
electronic system occurring in the Mn3+ ion. We take into account very strong
intra-atomic correlations, crystal field interactions and the intra-atomic
spin-orbit coupling. W... | 0403714v1 |
2004-04-08 | van der Waals energy under strong atom-field coupling in doped carbon nanotubes | Using a unified macroscopic QED formalism, we derive an integral equation for
the van der Waals energy of a two-level atomic system near a carbon nanotube.
The equation is valid for both strong and weak atom-vacuum-field coupling. By
solving it numerically, we demonstrate the inapplicability of
weak-coupling-based van ... | 0404211v1 |
2004-04-17 | Multiscale simulations in simple metals: a density-functional based methodology | We present a formalism for coupling a density functional theory-based quantum
simulation to a classical simulation for the treatment of simple metallic
systems. The formalism is applicable to multiscale simulations in which the
part of the system requiring quantum-mechanical treatment is spatially confined
to a small r... | 0404414v1 |
2004-05-04 | Transverse Electron Focusing in Systems with Spin-Orbit Coupling | We study the transverse electron focusing in a two dimensional electron gas
with Rashba spin-orbit coupling. We show that the interplay between the
external magnetic field and the spin-orbit coupling gives two branches of
states with different cyclotron radius within the same energy window. This
effect generates a spli... | 0405061v1 |
2004-05-12 | Noise-induced macroscopic bifurcations in globally-coupled chaotic units | Large populations of globally-coupled identical maps subjected to independent
additive noise are shown to undergo qualitative changes as the features of the
stochastic process are varied. We show that for strong coupling, the collective
dynamics can be described in terms of a few effective macroscopic degrees of
freedo... | 0405251v1 |
2004-05-21 | Analyzing Stability of Equilibrium Points in Neural Networks: A General Approach | Networks of coupled neural systems represent an important class of models in
computational neuroscience. In some applications it is required that
equilibrium points in these networks remain stable under parameter variations.
Here we present a general methodology to yield explicit constraints on the
coupling strengths t... | 0405505v1 |
2004-06-23 | Time-Resolved Detection of Individual Electrons in a Quantum Dot | We present measurements on a quantum dot and a nearby, capacitively coupled,
quantum point contact used as a charge detector. With the dot being weakly
coupled to only a single reservoir, the transfer of individual electrons onto
and off the dot can be observed in real time in the current signal from the
quantum point ... | 0406568v2 |
2004-06-28 | Synchronization by Nonlinear Frequency Pulling | We analyze a model for the synchronization of nonlinear oscillators due to
reactive coupling and nonlinear frequency pulling motivated by the physics of
arrays of nanoscale oscillators. We study the model for the mean field case of
all-to-all coupling, deriving results for the onset of synchronization as the
coupling o... | 0406673v1 |
2004-07-06 | Theory of Edge States in Systems with Rashba Spin-Orbit Coupling | We study the edge states in a two dimensional electron gas with a transverse
magnetic field and Rashba spin-orbit coupling. In the bulk, the interplay
between the external field perpendicular to the gas plane and the spin-orbit
coupling leads to two branches of states that, within the same energy window,
have different... | 0407138v1 |
2004-07-28 | Effects of Quantum-Well Inversion Asymmetry on Electron-Nuclear Spin Coupling in the Fractional Quantum Hall Regime | We examine effects of inversion asymmetry of a GaAs/Al0.3Ga0.7As quantum well
(QW) on electron-nuclear spin coupling in the fractional quantum Hall (QH)
regime. Increasing the QW potential asymmetry at a fixed Landau-level filling
factor (nu) with gate voltages suppresses the current-induced nuclear spin
polarization i... | 0407729v1 |
2004-07-29 | Thermodynamics of a Spin-1/2 Chain Coupled to Einstein Phonons | A high order series expansion is employed to study the thermodynamical
properties of a S=1/2 chain coupled to dispersionless phonons. The results are
obtained without truncating the phonon subspace since the series expansion is
performed formally in the overall exchange coupling J. The results are used to
investigate v... | 0407744v1 |
2004-08-26 | Large Magnetoresistance Induced by Quantum Charge Fluctuations in Magnetic Double Dots | We study electron tunneling through two small ferromagnetic dots. Quantum
charge fluctuations and interdot coupling make each Coulomb peak of the
conductance at zero interdot coupling split across. The interdot tunnel
coupling is determined by the relative orientation of magnetizations of the two
dots, leading to diffe... | 0408554v1 |
2004-08-27 | Effects of antiferromagnetic planes on the superconducting properties of multilayered high-Tc cuprates | We propose a mechanism for high critical temperature (T_c) in the coexistent
phase of superconducting- (SC) and antiferromagnetic (AF) CuO_2 planes in
multilayered cuprates. The Josephson coupling between the SC planes separated
by an AF insulator (Mott insulator) is calculated perturbatively up to the
fourth order in ... | 0408595v2 |
2004-09-01 | Modulational Instabilities and Domain Walls in Coupled Discrete Nonlinear Schrödinger Equations | We consider a system of two discrete nonlinear Schr\"{o}dinger equations,
coupled by nonlinear and linear terms. For various physically relevant cases,
we derive a modulational instability criterion for plane-wave solutions. We
also find and examine domain-wall solutions in the model with the linear
coupling. | 0409009v1 |
2004-09-07 | Weak vs. Strong Coupling in a Feshbach-Resonant Gas of Degenerate Fermi Atoms | This paper has been withrawn because one of us (MM) calculated the wrong
density for the JILA experiments, leading to the incorrect conclusion that said
experiments could be considered as weakly-coupled and, thus, molecule rich. | 0409164v2 |
2004-09-16 | Anisotropic Electron-Phonon Coupling Uncovered By Angle-Resolved Photoemission | Recently there has been an accumulation of experimental evidence in the high
temperature superconductors suggesting the relevance of electron-phonon
coupling in these materials. These findings challenge some well-held beliefs of
what electron-phonon interactions can and cannot do. In this article we review
evidence pri... | 0409426v1 |
2004-09-25 | Competing effects of interactions and spin-orbit coupling in a quantum wire | We study the interplay of electron-electron interactions and Rashba
spin-orbit coupling in one-dimensional ballistic wires. Using the
renormalization group approach we construct the phase diagram in terms of
Rashba coupling, Tomonaga-Luttinger stiffness and backward scattering strength.
We identify the parameter regime... | 0409678v2 |
2004-10-03 | Spin-Orbit Effects in Diluted Magnetic Semiconductors | We present a theoretical study of diluted magnetic semiconductors that treats
the local sp-d exchange interaction J between the itinerant carriers and the Mn
d electrons within a realistic band structure and goes beyond previous
mean-field approaches. In case of (Ga,Mn)As, we find that strong exchange
potentials tightl... | 0410051v1 |
2004-10-22 | Thomas-Fermi Theory of the Hyperfine Constants of Endohedral Fullerene Atoms | We present a modified Thomas-Fermi theory that describes the increase of the
hyperfine coupling constants of endohedrally enclosed atoms. We use the March
boundary conditions corresponding to a positively charged spherical shell
surrounding the nuclear potential to represent the effect of the fullerene
shell. We obtain... | 0410566v1 |
2004-12-09 | Entanglement distillation by adiabatic passage in coupled quantum dots | Adiabatic passage of two correlated electrons in three coupled quantum dots
is shown to provide a robust and controlled way of distilling, transporting and
detecting spin entanglement, as well as of measuring the rate of spin
disentanglement. Employing tunable interdot coupling the scheme creates, from
an unentangled t... | 0412229v1 |
2004-12-28 | Synchronization in scale-free network with asymmetric coupling | The propensity for synchronization is studied in a complex network of
asymmetrically coupled units, where the asymmetry in a given link is determined
by the relative age of the involved nodes. In growing scale-free networks
synchronization is enhanced when couplings from older to younger nodes are
dominant. We describe... | 0412728v1 |
2005-01-14 | Fokker-Planck equation for coupled anharmonic oscillators: symplectic integration and application to mean-field model of cooperative behavior | Kinetics of systems specified by anharmonic, nonconservative and nonlocally
coupled model Hamiltonians is reproduced in the Fokker-Planck and imaginary
time Schrodinger equation techniques with subsequent symplectic integration.
Test solutions focused on dielectric response in ferroelectrics demonstrates
potential of t... | 0501339v1 |
2005-02-09 | Reply to the comment by D. Gorokhov cond-mat/0502083 | We show that the recent comment by D. Gorokhov, is based on physically
obvious errors and misunderstandings of the content of the criticized papers
and is readily refuted. We show that 1) In our paper [1] there were considered
situations of both strong and weak interband coupling regimes. 2) In the ref
[1] it was given... | 0502250v1 |
2005-02-16 | Vanishing of the Dissipationless Spin Hall Effect in a Diffusive Two-Dimensional Electron Gas with Spin-Orbit Coupling | We propose a nonequilibrium Green's function approach to study the spin-Hall
effect in a two-dimensional electron system with both the Rashba and
Dresselhaus spin-orbit couplings. By taking into account the long-range
electron-impurity scattering, the derived kinetic equations are solved
numerically. It is found the va... | 0502392v1 |
2005-03-07 | Ab initio analysis of electron-phonon coupling in molecular devices | We report first principles analysis of electron-phonon coupling in molecular
devices under external bias voltage and during current flow. Our theory and
computational framework are based carrying out density functional theory within
the Keldysh nonequilibrium Green's function formalism. We analyze which
molecular vibra... | 0503157v2 |
2005-03-10 | Pseudospin and Quantum Computation in Semiconductor Nanostructures | We review the theoretical aspects of pseudospin quantum computation using
vertically coupled quantum dots in the quantum Hall regime. We discuss the
robustness and addressability of these collective, charge-based qubits. The low
energy Hilbert space of a coupled set of qubits yields an effective quantum
Ising model tun... | 0503257v2 |
2005-03-29 | Pairing and polarization in systems with retarded interactions | In a system where a boson (e.g, a phonon) of finite frequency $\omega_0$ is
coupled to electrons, two phenomena occur as the coupling is increased:
electron pairing and polarization of the boson field. Within a path integral
formalism and a Dynamical Mean-Field approach, we introduce {\it ad hoc}
distribution function ... | 0503681v1 |
2005-04-07 | Finite E x beta Jahn-Teller Systems: A Continued-Fraction Approach | A recursive method is developed to treat electrons coupled to phonons. It is
applied to small systems with $E\otimes\beta$ Jahn-Teller coupling. Two cases
are considered, a model with one electron and two orbitals on a single site
(related to the Rabi Hamiltonian) and a model with two electrons on two sites.
The corres... | 0504164v1 |
2005-04-14 | Dephasing in quantum dot molecules via exciton-acoustic phonon coupling | We develop a theory of the linear optical spectrum of excitons in quantum dot
molecules, including the effect of exciton-phonon coupling beyond the Markov
limit. The model reproduces the general trend of the zero-phonon line
broadening as a function of interdot distance, that were recently measured. The
unexpectedly br... | 0504372v1 |
2005-05-02 | Quasi regular concentric waves in heterogeneous lattices of coupled oscillators | We study the pattern formation in a lattice of coupled phase oscillators with
quenched disorder. In the synchronized regime concentric waves can arise, which
are induced and increase in regularity by the disorder of the system. Maximal
regularity is found at the edge of the synchronization regime. The emergence of
the ... | 0505035v1 |
2005-05-04 | Probing the Kondo density of states in a three-terminal quantum ring | We have measured the Kondo effect in a quantum ring connected to three
terminals. In this configuration non-linear transport measurements allow to
check which lead contributes to the Kondo density of states (DOS) and which
does not. When the ring is connected to two strongly and one weakly coupled
leads, the measuremen... | 0505111v1 |
2005-05-12 | Modulational instability criteria for two-component Bose-Einstein condensates | The stability of colliding Bose-Einstein condensates is investigated. A set
of coupled Gross-Pitaevskii equations is thus considered, and analyzed via a
perturbative approach. No assumption is made on the signs (or magnitudes) of
the relevant parameters like the scattering lengths and the coupling
coefficients. The for... | 0505324v1 |
2005-06-09 | Screening in the two-dimensional electron gas with spin-orbit coupling | We study the interplay between electron-electron interaction and Rashba
spin-orbit coupling in the two-dimensional electron gas. Using the random phase
approximation we predict new screening properties of the electron gas which
result in extension of the region of particle-hole excitations and in
spin-orbit induced sup... | 0506227v2 |
2005-06-13 | Universal Scaling Relations in Strongly Anisotropic Materials | We consider the critical temperature in strongly anisotropic
antiferromagnetic materials, with weak coupling between stacked planes, in
order to determine the interplane coupling constant from experimentally
measured susceptibilities. We present theoretical arguments for a universal
relation between interplane coupling... | 0506294v1 |
2005-06-14 | Spin-wave softening and Hund's coupling in ferromagnetic manganites | Using one-orbital model of hole-doped manganites, we show with the help of
Holstein-Primakov transformation that finite Hund's coupling is responsible for
the spin-wave softening in the ferromagnetic $B$-phase manganites. We obtain an
analytical result for the spin-wave spectrum for $\JH\gg t$. In the limit of
infinte ... | 0506321v1 |
2005-06-15 | Direct observation of displaced phonons responsible for small polaron charge transport in (La1/3Sm2/3)0.67Ba0.33-xSrxMnO3 (x = 0.0, 0.1, 0.2 and 0.33) | It is shown that charge transport in substituted manganites
(La1/3Sm2/3)0.67Ba0.33-xSrxMnO3 (x = 0.0, 0.1, 0.2 and 0.33) is through
polarons which are formed through electron-phonon coupling whose strength
determines the mobility of the charge carrier. For weak coupling the free
phonon mode is only slightly affected bu... | 0506346v1 |
2005-06-16 | Design and control of spin gates in two quantum dots arrays | We study the spin-spin interaction between quantum dots coupled through a two
dimensional electron gas with spin-orbit interaction. We show that the
interplay between transverse electron focusing and spin-orbit coupling allows
to dynamically change the symmetry of the effective spin-spin Hamiltonian. That
is, the inter... | 0506414v1 |
2005-06-20 | Electronic and magnetic properties of a hexanuclear ferric wheel | The electronic and magnetic properties of the hexanuclear ferric wheel
[LiFe6(OCH3)12-(dbm)6]PF6 have been studied with all-electron Hartree-Fock and
full-potential density functional calculations. The best agreement for the
magnetic exchange coupling is at the level of the B3LYP hybrid functional.
Surprisingly, the Ha... | 0506486v1 |
2005-07-01 | Spin-orbit coupling and spin transport | Recent achievements in semiconductor spintronics are discussed. Special
attention is paid to spin-orbit interaction, coupling of electron spins to
external electric fields, and spin transport in media with spin-orbit coupling,
including the mechanisms of spin-Hall effect. Importance of spin-transport
parameters at spin... | 0507007v2 |
2005-07-07 | Dynamical properties of temperature chaos and memory effect | In the frustrated interaction systems, the nature of ordered configuration
can be intrinsically temperature dependent. There, the idea of effective
coupling of decorated and frustrated bond plays an important role. The idea of
effective coupling is verified in the study of equilibrium properties. We will
study how the ... | 0507161v3 |
2005-07-13 | Dynamics of Coupled Topological - Collective Modes of a Bose-Einstein Condensate | We develop the theory of the resonant formation of coupled
topological-collective coherent modes in the presence of a quantized trap and
classical external field. The coupling between the topological and the
collective modes can be linear as well as non-linear depending upon the tuning
of the external extremely low fre... | 0507306v1 |
2005-07-15 | Tunnel magnetoresistance of quantum dots coupled to ferromagnetic leads in the sequential and cotunneling regimes | We study electronic transport through quantum dots weakly coupled to
ferromagnetic leads with collinear magnetization directions. Tunneling
contributions of first and second order in the tunnel-coupling strength are
taken into account. We analyze the tunnel magnetoresistance (TMR) for all
combinations of linear and non... | 0507357v1 |
2005-07-22 | Kondo Resonance Decoherence by an External Potential | The Kondo problem, for a quantum dot (QD), subjected to an external bias, is
analyzed in the limit of infinite Coulomb repulsion by using a consistent
equations of motion method based on a slave-boson Hamiltonian. Utilizing a
strict perturbative solution in the leads-dot coupling, T, to T^4 and T^6
orders, we calculate... | 0507518v1 |
2005-08-20 | Internal space renormalization group for the Luttinger model | The absence of fermionic, asymptotical one-particle states in the Luttinger
model raises the suspicion that the interactions are actually strong at the
vicinity of the Fermi points. The functional internal space renormalization
group method, a systematical scheme for the computation of effective coupling
strengths off ... | 0508491v1 |
2005-08-31 | Electrostatic Interactions in Strongly-Coupled Soft Matter | Charged soft-matter systems--such as colloidal dispersions and charged
polymers--are dominated by attractive forces between constituent like-charged
particles when neutralizing counterions of high charge valency are introduced.
Such counter-intuitive effects indicate strong electrostatic coupling between
like-charged p... | 0508767v1 |
2005-09-09 | Thermodynamic properties of the XX model in a chain with a period two and three coupling | The exact solutions for the energy spectrum of the XX model with a periodic
coupling and an external transverse magnetic field $h$ are obtained. The
diagonalization procedure is discussed, and analytical and numerical solutions
are given. Using the solutions for period-two coupling, the free energy,
entropy, and specif... | 0509250v2 |
2005-09-12 | Numerical Studies of the Compressible Ising Spin Glass | We study a two-dimensional compressible Ising spin glass at constant volume.
The spin interactions are coupled to the distance between neighboring particles
in the Edwards-Anderson model with +/- J interactions. We find that the energy
of a given spin configuration is shifted from its incompressible value, E_0, by
an a... | 0509280v1 |
2005-09-26 | Tunneling out of metastable vacuum in a system consisting of two capacitively coupled phase qubits | Using a powerful combination of Coleman's instanton technique and the method
of Banks and Bender, the exponential factor for the zero temperature rate of
tunneling out of metastable vacuum in a system of two identical capacitively
coupled phase qubits is calculated in closed form to second order in asymmetry
parameter ... | 0509659v3 |
2005-09-28 | Quantum transport phenomena in disordered electron systems with spin-orbit coupling in two dimensions and below | Electron transport phenomena in disordered electron systems with spin-orbit
coupling in two dimensions and below are studied numerically. The scaling
hypothesis is checked by analyzing the scaling of the quasi-1D localization
length. A logarithmic increase of the mean conductance is also confirmed. These
support the th... | 0509718v1 |
2005-09-28 | Magnetic properties of antiferromagnetically coupled CoFeB/Ru/CoFeB | This work reports on the thermal stability of two amorphous CoFeB layers
coupled antiferromagnetically via a thin Ru interlayer. The saturation field of
the artificial ferrimagnet which is determined by the coupling, J, is almost
independent on the annealing temperature up to more than 300 degree C. An
annealing at mor... | 0509753v1 |
2005-10-03 | Thermoelectric effects in strongly interacting quantum dot coupled to ferromagnetic leads | We study thermoelectric effects in Kondo correlated quantum dot coupled to
ferromagnetic electrodes by calculating conductance, thermopower and thermal
conductance in the Kondo regime. We also study the effect of the asymmetry in
the coupling to the leads, which has important consequences for anti-parallel
magnetizatio... | 0510036v1 |
2005-10-12 | Magnetodielectric effect without multiferroic coupling | The existence of a magnetodielectric (magnetocapacitance) effect is often
used as a test for multiferroic behavior in new material systems. However,
strong magnetodielectric effects can also be achieved through a combination of
magnetoresistance and the Maxwell-Wagner effect, unrelated to multiferroic
coupling. The fac... | 0510313v1 |
2005-10-19 | Dynamics and thermodynamics of rotators interacting with both long and short range couplings | The effect of nearest-neighbor coupling on the thermodynamic and dynamical
properties of the ferromagnetic Hamiltonian Mean Field model (HMF) is studied.
For a range of antiferromagnetic nearest-neighbor coupling, a canonical first
order transition is observed, and the canonical and microcanonical ensembles
are non-equ... | 0510508v1 |
2005-10-28 | Infrared absorption and Raman scattering on coupled plasmon--phonon modes in superlattices | We consider theoretically a superlattice formed by thin conducting layers
separated spatially between insulating layers. The dispersion of two coupled
phonon-plasmon modes of the system is analyzed by using Maxwell's equations,
with the influence of retardation included. Both transmission for the finite
plate as well a... | 0510784v1 |
2005-11-03 | Electron-phonon coupling and spin-charge separation in one-dimensional Mott insulators | We examine the single-particle excitation spectrum in the one-dimensional
Hubbard-Holstein model at half-filling by performing the dynamical density
matrix renormalization group (DDMRG) calculation. The DDMRG results are
interpreted as superposition of spectra for a spinless carrier dressed with
phonons. The superposit... | 0511068v1 |
2005-11-07 | Effect of the intrinsic Josephson coupling on the pancake lattice in layered superconductors | We study the pancake lattice system induced by application of transverse
magnetic filed to the layered superconductor. A simple statistical field theory
for the pancake lattice is derived. It incorporates effects of the magnetic
interaction between pancakes as well as those of the interlayer Josephson
coupling. The pro... | 0511155v1 |
2005-11-07 | Non-equilibrium triplet blockade in parallel coupled quantum dots | It is demonstrated that parallel weakly coupled quantum dots exhibit
non-equilibrium blockade regimes caused by a full occupation in the spin
triplet state, in analogy to the Pauli spin blockade in serially weakly coupled
quantum dots. Charge tends to accumulate in the two-electron triplet for bias
voltages that suppor... | 0511165v3 |
2005-11-15 | Magnetization plateaux induced by a coupling to the lattice | We investigate a simple model of a frustrated spin-1/2 Heisenberg chain
coupled to adiabatic phonons under an external magnetic field. Using field
theoretic methods complemented by extensive Density Matrix Renormalisation
Group techniques generalized to include self-consistent lattice distortions, we
show that magnetiz... | 0511368v1 |
2005-11-22 | Entanglement production in chaotic quantum dots subject to spin-orbit coupling | We study numerically the production of orbital and spin entangled states in
chaotic quantum dots for non-interacting electrons. The introduction of
spin-orbit coupling permit us to identify signatures of time-reversal symmetry
correlations in the entanglement production previously unnoticed, resembling
weak-(anti)local... | 0511555v3 |
2005-11-28 | Stable isochronal synchronization of mutually coupled chaotic lasers | The dynamics of two mutually coupled chaotic diode lasers are investigated
experimentally and numerically. By adding self feedback to each laser, stable
isochronal synchronization is established. This stability, which can be
achieved for symmetric operation, is essential for constructing an optical
public-channel crypt... | 0511648v1 |
2005-12-14 | Piezoelectric coupling, phonons, and tunneling into a quantum Hall edge | We show that the piezoelectric coupling to three-dimensional phonons in GaAs
renormalizes the current-voltage exponent for tunneling of electrons into an
incompressible quantum Hall edge. The leading correction is always negative, in
agreement with experiments on the $\nu = 1/3$ state and, depending on the
precise valu... | 0512320v1 |
2005-12-19 | Transport of Single Molecules Along the Periodic Parallel Lattices with Coupling | General discrete one-dimensional stochastic models to describe the transport
of single molecules along coupled parallel lattices with period $N$ are
developed. Theoretical analysis that allows to calculate explicitly the
steady-state dynamic properties of single molecules, such as mean velocity $V$
and dispersion $D$, ... | 0512482v1 |
2006-01-02 | Crystal field, spin-orbit coupling and magnetism in a ferromagnet YTiO3 | Magnetic properties of stechiometric YTiO3 has been calculated within the
single-ion-based paradigm taking into account the low-symmetry crystal field
and the intra-atomic spin-orbit coupling of the Ti3+ ion. Despite of the very
simplified approach the calculations reproduce perfectly the value of the
magnetic moment a... | 0601005v1 |
2006-01-17 | Effects of multiplicative noises on synchronization in finite $N$-unit stochastic ensembles: Augmented moment approach | We have studied the synchronization in finite $N$-unit FitzHugh-Nagumo neuron
ensembles subjected to additive and multiplicative noises, by using the
augmented moment method (AMM) which is reformulated with the use of the
Fokker-Planck equation. It has been shown that for diffusive couplings, the
synchronization may be... | 0601358v1 |
2006-01-17 | Noise Thermometry with Two Weakly Coupled Bose-Einstein Condensates | Here we report on the experimental investigation of thermally induced
fluctuations of the relative phase between two Bose-Einstein condensates which
are coupled via tunneling. The experimental control over the coupling strength
and the temperature of the thermal background allows for the quantitative
analysis of the ph... | 0601392v2 |
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