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cond-mat/9503053
Excitons in soliton and bipolaron lattice states of doped Peierls systems
Exciton effects on soliton and bipolaron lattice states are investigated using an electron-lattice Peierls model with long-range Coulomb interactions. The Hartree-Fock (HF) approximation and the single-excitation configuration-interaction (single-CI) method are used to obtain optical absorption spectra. We discuss the ...
1995-03-09
2007-05-23
[ "cond-mat", "chem-ph", "mtrl-th" ]
Kikuo Harigaya, Yukihiro Shimoi, Shuji Abe
cond-mat/9503048
Spin Dynamics of the Triangular Heisenberg Antiferromagnet: A Schwinger Boson Approach
We have analyzed the two-dimensional antiferromagnetic Heisenberg model on the triangular lattice using a Schwinger boson mean-field theory. By expanding around a state with local $120^\circ$ order, we obtain, in the limit of infinite spin, results for the excitation spectrum in complete agreement with linear spin wave...
1995-03-09
2016-08-31
[ "cond-mat" ]
Ann Mattsson
cond-mat/9503039
Screening effect of interlayer coupling on electronic transport properties of layered high-$T_c$ oxides
We have investigated the effect of thermal fluctuation on the interlayer coupling of three-dimensional Josephson-junction arrays with anisotropic interactions as a model of layered high-$T_c$ oxides, focusing on non-Ohmic current-voltage characteristics. Langevin dynamic simulations were performed for various Josephson...
1995-03-08
2016-08-31
[ "cond-mat" ]
R. Sugano, T. Onogi, and Y. Murayama
cond-mat/9503044
Model of C-Axis Resistivity of High-$\Tc$ Cuprates
We propose a simple model which accounts for the major features and systematics of experiments on the $c$-axis resistivity, $\rho_c$, for $\lsco$, $\ybco$ and $\bsco $. We argue that the $c$-axis resistivity can be separated into contributions from in-plane dephasing and the $c$-axis ``barrier'' scattering processes, w...
1995-03-08
2016-08-31
[ "cond-mat" ]
Yuyao Zha, S. L. Cooper and David Pines
cond-mat/9503043
Plastic energies in layered superconductors
We estimate the energy cost associated with two pancake vortices colliding in a layered superconductor. It is argued that this energy sets the plastics energy scale and is the analogue of the crossing energy for vortices in the continuum case. The starting point of the calculation is the Lawrence-Doniach version of the...
1995-03-08
2016-08-31
[ "cond-mat" ]
N.K. Wilkin and M.A. Moore
cond-mat/9503041
Critical Behavior of the 3d Random Field Ising Model: Two-Exponent Scaling or First Order Phase Transition?
In extensive Monte Carlo simulations the phase transition of the random field Ising model in three dimensions is investigated. The values of the critical exponents are determined via finite size scaling. For a Gaussian distribution of the random fields it is found that the correlation length $\xi$ diverges with an expo...
1995-03-08
2009-10-28
[ "cond-mat", "hep-lat" ]
Heiko Rieger
cond-mat/9503040
Tunneling Between Two-Dimensional Electron Gases in a Weak Magnetic Field
We have measured the tunneling between two two-dimensional electron gases (2DEGs) in weak magnetic fields, when the carrier densities of the two electron layers are matched. At zero magnetic field, B=0, the lineshape of the equilibrium tunneling resonance is best fit by a Lorentzian, with a linewidth which is determine...
1995-03-08
2007-05-23
[ "cond-mat" ]
N. Turner, J. T. Nicholls, K. M. Brown, E. H. Linfield, M. Pepper, D. A. Ritchie, and G. A. C. Jones (Cavendish Laboratory, Cambridge)
cond-mat/9503042
On the Plasmon-like Excitations of Atomic Clusters with Application to Fullerene
We present here a modified hydrodynamical model for the collective electronic excitations of spherical atomic clusters. The model is applied to the giant-dipole plasmon mode of the free fullerene molecule.
1995-03-08
2007-05-23
[ "cond-mat" ]
B. Carazza (Physics Dept. Parma Italy)
cond-mat/9503047
A Rigorous Analysis of the Superconducting Phase of an Electron - Phonon System
In these notes we give a very rough sketch of nonperturbative methods of many body quantum field theory that are powerful enough to rigorously control weak coupling instabilities in condensed matter phyics, for example, the Cooper instability in an electron - phonon system.
1995-03-08
2016-08-31
[ "cond-mat", "hep-th" ]
Joel Feldman (Univ of British Columbia), Jacques Magnen (Ecole Polytechnique), Vincent Rivasseau (Ecole Polytechnique), and Eugene Trubowitz (ETH)
cond-mat/9503030
Vortex, Defect, and Monopole Gauge Fields for Nambu-Goldstone Systems and their Phase Transitions or Theory of Fluctuating Multivalued Fields
We survey the various uses of singular gauge fields which render an ideal description of ensembles of line- and surface-like excitations and explain phase transitions with the help of simple quadratic actions. Near a transition, the singular gauge fields can be transformed into ordinary complex fields called disorder f...
1995-03-07
2016-08-15
[ "cond-mat" ]
H. Kleinert (Institut f\"ur Theoretische Physik Freie Universit\"at)
cond-mat/9503033
SCHR\"ODINGER INVARIANCE IN DISCRETE STOCHASTIC SYSTEMS
Local scale invariance for lattice models is studied using new realizations of the Schr\"odinger algebra. The two-point function is calculated and it turns out that the result can be reproduced from exact two-point correlation functions evaluated in the stationary state of several simple stochastic models.
1995-03-07
2015-06-25
[ "cond-mat" ]
Malte Henkel and Gunter Sch\"utz
cond-mat/9503031
Anisotropic Spin-1/2 Heisenberg Chain with Open Boundary Conditions
We study the exact solution of the XXZ spin-1/2 Heisenberg chain with a boundary magnetic field in the region where the bulk excitations are gapless. It is shown that a bound state is created near the boundary with a total spin $S = 1/2(\pi/\gamma - 1)$ where $\cos\gamma$ is the anisotropy parameter. When $\gamma < \pi...
1995-03-07
2015-06-25
[ "cond-mat" ]
P. de Sa and A. M. Tsvelik
cond-mat/9503032
Randomly Charged Polymers: An Exact Enumeration Study
We perform an exact enumeration study of polymers formed from a (quenched) random sequence of charged monomers $\pm q_0$. Such polymers, known as polyampholytes, are compact when completely neutral and expanded when highly charged. Our exhaustive search included all spatial conformations and quenched sequences for up t...
1995-03-07
2009-10-28
[ "cond-mat" ]
Yacov Kantor and Mehran Kardar
cond-mat/9503035
Delocalization of electrons in a Random Magnetic Field
Delocalization problem for a two-dimensional non-interacting electron system is studied under a random magnetic field. With the presence of a random magnetic field, the Hall conductance carried by each eigenstate can become nonzero and quantized in units of $e^2/h$. Extended states are characterized by nonzero Hall con...
1995-03-07
2016-08-31
[ "cond-mat" ]
D.N. Sheng and Z. Y. Weng
cond-mat/9503037
GINZBURG-LANDAU THEORY OF VORTICES IN $d$-WAVE SUPERCONDUCTORS
Ginzburg-Landau theory is used to study the properties of single vortices and of the Abrikosov vortex lattice in a $d_{x^2-y^2}$ superconductor. For a single vortex, the $s$-wave order parameter has the expected four-lobe structure in a ring around the core and falls off like $1/r^2$ at large distances. The topological...
1995-03-07
2016-08-31
[ "cond-mat", "supr-con" ]
A.J. Berlinsky, A.L. Fetter, M. Franz, C. Kallin, and P.I. Soininen
cond-mat/9503034
Dislocations in uniaxial lamellar phases of liquid crystals, polymers and amphiphilic systems
Dislocations in soft condensed matter systems such as lamellar systems of polymers, liquid crystals and ternary mixtures of oil, water and surfactant (amphiphilic systems) are described in the framework of continuum elastic theory. These systems are the subject of studies of physics, chemistry and biology. They also fi...
1995-03-07
2015-06-25
[ "cond-mat" ]
R.Holyst and P.Oswald
cond-mat/9503036
Possible disordered ground states for close-packed polytypes and their diffraction patterns
It has recently been shown that one-dimensional Ising problems can have degenerate, disordered ground states (GSs) over a finite range of coupling onstants, ie, without `fine tuning'. The disorder is however of a special kind, consisting of arbitrary mixtures of a short-period structure and its symmetry-degenerate part...
1995-03-07
2016-08-31
[ "cond-mat" ]
Jaichul Yi and Geoff S. Canright
cond-mat/9503026
Comment on " Thermodynamics of a One- Dimensional Ideal Gas with fractional Exclusion Statistics "
In a recent letter -Phys. Rev. Lett. 73, 3331 (1995)-, the conclusion was reached that, in the one-dimensional Calogero model, only the second virial coefficient is affected by the statistical parameter $\alpha$, where $\alpha$ is related to the coupling constant $\kappa/ x_{ij}^2$ of the Calogero interaction by $\kapp...
1995-03-06
2016-08-31
[ "cond-mat" ]
Alain DASNI\`ERES de VEIGY and St\'ephane OUVRY, Division de Physique Th\'eorique, IPN, Orsay Fr-91406
cond-mat/9503025
Quantum critical phenomena in ladders of Josephson junctions in a magnetic field
A model of a ladder of Josephson junctions in a magnetic field is considered. The topological features of the zero-temperature phase diagram, as a function of charging energy and small deviations from commensurability of the vortex lattice, are strongly dependent on the field. In addition to superconductor-insulator tr...
1995-03-06
2016-08-31
[ "cond-mat", "supr-con" ]
Enzo Granato
cond-mat/9503028
Continuum limit, Galilean invariance, and solitons in the quantum equivalent of the noisy Burgers equation
A continuum limit of the non-Hermitian spin-1/2 chain, conjectured recently to belong to the universality class of the noisy Burgers or, equivalently, Kardar-Parisi-Zhang equation, is obtained and analyzed. The Galilean invariance of the Burgers equation is explicitly realized in the operator algebra. In the quasi-clas...
1995-03-06
2009-10-28
[ "cond-mat" ]
Hans C. Fogedby, Anders B. Eriksson, Lev V. Mikheev
cond-mat/9503029
Phase Transition, Longitudinal Spin Fluctuations and Scaling in a Two-Layer Antiferromagnet
We consider a two-layer Heisenberg antiferromagnet which can be either in the N\'{e}el-ordered or in the disordered phase at $T=0$, depending on the ratio of the intra- and interlayer exchange constants. We reduce the problem to an interacting Bose-gas and study the sublattice magnetization and the transverse susceptib...
1995-03-06
2016-08-31
[ "cond-mat" ]
Andrey V. Chubukov and Dirk K. Morr
cond-mat/9503027
An Exactly Soluble Model of Directed Polymers with Multiple Phase Transitions
Polymer chains with hard-core interaction on a two-dimensional lattice are modeled by directed random walks. Two models, one with intersecting walks (IW) and another with non-intersecting walks (NIW) are presented, solved and compared. The exact solution of the two models, based on a representation using Grassmann vari...
1995-03-06
2016-08-31
[ "cond-mat" ]
G. Forgacs and K. Ziegler
cond-mat/9503023
On thermoelastic phenomena around orientational ordering transition in crystalline C60
Thermoelastic phenomena associated with orientational phase transition in solid C60 are considered. Coupling of the order parameter with elastic strain is analyzed in the Landau theory of phase transitions. Wide range of possible coexistence of the FCC phase with SC one in C60 has been found from 260 K down to critical...
1995-03-05
2016-08-31
[ "cond-mat", "chem-ph", "mtrl-th" ]
M.A.Fradkin
cond-mat/9503022
Transitions Between Hall Plateaus and the Dimerization Transition of a Hubbard Chain
We show that the plateau transitions in the quantum Hall effect is the same as the dimerization transition of a half-filled, one dimensional, $U(2n)$ Hubbard model at $n=0$. We address the properties of the latter by a combination of perturbative renormalization group and Monte Carlo simulations. Results on both critic...
1995-03-04
2015-06-25
[ "cond-mat" ]
Dung-Hai Lee and Ziqiang Wang
cond-mat/9503024
From ODLRO to the Meissner Effect and Flux Quantization
It has been shown that the electron system with ODLRO in the reduced density matrix $\rho _2$ can not support a uniform magnetic field, i.e., ODLRO\ in $% \rho _2$ implies the Meissner effect \cite{2}\cite{3}, furthermore, the magnetic field trapped in the system is quantized\cite{3}. This note extends above results in...
1995-03-04
2016-08-31
[ "cond-mat" ]
Chi Au and Bao-Heng Zhao
cond-mat/9503021
BCS-Universal Ratios within the Van Hove Scenario
The central result of BCS theory are the Universal Ratios which do not depend on physical parameters of the superconductor under study. Several attempts have been made to introduce the van Hove Scenario within BCS theory but in none of them the Universal Ratios of conventional superconductivity appear to be a number in...
1995-03-03
2009-10-28
[ "cond-mat" ]
R. Baquero, D. Quesada, C. Trallero-Giner
cond-mat/9503020
Energy Barriers to Motion of Flux Lines in Random Media
We propose algorithms for determining both lower and upper bounds for the energy barriers encountered by a flux line in moving through a two-dimensional random potential. Analytical arguments, supported by numerical simulations, suggest that these bounds scale with the length $t$ of the line as $t^{1/3}$ and $t^{1/3}\s...
1995-03-03
2016-08-31
[ "cond-mat" ]
Lev V. Mikheev (Nordita), Barbara Drossel and Mehran Kardar (MIT)
cond-mat/9503018
Replica Symmetry Breaking in Renormalization: Application to the Randomly Pinned Planar Flux Array
The randomly pinned planar flux line array is supposed to show a phase transition to a vortex glass phase at low temperatures. This transition has been examined by using a mapping onto a 2D XY-model with random an\-iso\-tropy but without vortices and applying a renormalization group treatment to the replicated Hamilton...
1995-03-03
2016-08-31
[ "cond-mat" ]
Jan Kierfeld (Universit\"at K\"oln)
cond-mat/9503019
Critical Exponents of the Superconducting Phase Transition
We study the critical exponents of the superconducting phase transition in the context of renormalization group theory starting from a dual formulation of the Ginzburg-Landau theory. The dual formulation describes a loop gas of Abrikosov flux tubes which proliferate when the critical temperature is approached from belo...
1995-03-03
2016-08-31
[ "cond-mat", "supr-con" ]
Michael Kiometzis, Hagen Kleinert, and Adriaan M. J. Schakel (Institut f\"ur Theoretische Physik, Freie Universit\"at Berlin)
cond-mat/9503038
Exact Five-Loop Renormalization Group Functions of $\phi^4$-Theory with O(N)-Symmetric and Cubic Interactions. Critical Exponents up to $\ep^5$
The renormalization group functions are calculated in $D=4-\epsilon$ dimensions for the $\phi^4$-theory with two coupling constants associated with an ${O}(N)$-symmetric and a cubic interaction. Divergences are removed by minimal subtraction. The critical exponents $\eta$, $\nu$, and $\omega$ are expanded up to order $...
1995-03-03
2009-10-28
[ "cond-mat" ]
H. Kleinert and V. Schulte-Frohlinde (Institut f\"ur Theoretische Physik, Freie Universit\"at Berlin)
cond-mat/9503014
Inter-Edge interaction in the Quantum Hall Effect
We consider effects of the interaction between electrons drifting along the opposite sides of a narrow sample under the conditions of the quantum Hall effect. A spatial variation of this interaction leads to backward scattering of collective excitations propagating along the edges. Experiments on propagation of the edg...
1995-03-02
2016-08-31
[ "cond-mat" ]
Yuval Oreg and Alexander M. Finkel'stein
cond-mat/9503017
On $K_0$-Groups for Substitution Tilings
The group $C(\Om,\Z)/\E$ is determined for tilings which are invariant under a locally invertible primitive \sst\ which forces its \saum. In case the tiling may be obtained by the generalized dual method from a regular grid this group furnishes part of the $K_0$-group of the algebra of the tiling. Applied to Penrose ti...
1995-03-02
2016-08-31
[ "cond-mat", "hep-th" ]
Johannes Kellendonk
cond-mat/9503010
Resonant two-magnon Raman scattering in parent compounds of high-T$_c$ superconductors.
We propose a theory of two-magnon Raman scattering from the insulating parent compounds of high-T$_c$ superconductors, which contains information not only on magnetism, but also on the electronic properties in these materials. We use spin density wave formalism for the Hubbard model, and study diagrammatically the prof...
1995-03-02
2016-08-31
[ "cond-mat" ]
Andrey V. Chubukov and David M. Frenkel
cond-mat/9503012
Neutron Scattering and $d$-Wave Symmetry in the Cuprates
In this comment we demonstrate that the general conjectures of Fong $et~ al$ on their ${\rm YBa_2Cu_3O_7}$ neutron experiments are realized in concrete calculations of the neutron scattering structure factor $S({\bf q} , \omega )$ in this material. We make predictions for similar experiments in ${\rm La_2Sr_{0.15}Cu_{1...
1995-03-02
2016-08-31
[ "cond-mat" ]
Yuyao Zha and K. Levin
cond-mat/9503011
Coadsorption of Copper and Sulfate on Au(111) Electrodes: Monte Carlo Simulation of a Lattice-Gas Model
We report ground-state calculations and Monte Carlo simulations for a lattice-gas model of the underpotential deposition of copper on Au(111) in sulfate-containing electrolytes. In a potential range of approximately 100$\sim$150 mV, this system exhibits a $(\sqrt3\!\times\!\sqrt3)$ mixed phase with 2/3 monolayer (ML) c...
1995-03-02
2016-08-31
[ "cond-mat", "chem-ph" ]
J. Zhang, P.A. Rikvold, Y.-E. Sung, and A. Wieckowski
cond-mat/9503016
On the Four-Dimensional Diluted Ising Model
In this letter we show strong numerical evidence that the four dimensional Diluted Ising Model for a large dilution is not described by the Mean Field exponents. These results suggest the existence of a new fixed point with non-gaussian exponents.
1995-03-02
2009-10-28
[ "cond-mat", "hep-lat" ]
Giorgio Parisi and Juan J. Ruiz-Lorenzo
cond-mat/9503015
Structural Transition Models for a class of Irreversible Aggregates
A progress report on two recent theoretical approaches proposed to understand the physics of irreversible fractal aggregates showing up a structural transition from a rather dense to a more multibranched growth is presented. In the first approach the transition is understood by solving the Poisson equation on a squared...
1995-03-02
2008-08-31
[ "cond-mat" ]
E. Canessa
cond-mat/9503002
A Scenario to the Anomalous Hall Effect in the Mixed State of Superconductors
We argue that the motion of vacancies in a pinned vortex lattice may dominate the contribution to the Hall effect in an appropriate parameter regime for a superconductor. Based on this consideration a model is constructed to explain the anomalous Hall effect without any modification of the basic vortex dynamic equation...
1995-03-01
2016-08-31
[ "cond-mat" ]
Ping Ao
cond-mat/9503007
Wigner Crystals Phases in Bilayer Quantum Hall Systems
(This is a substantially shortened version of the original abstract:) The Wigner crystal phase diagram of the bilayer systems have been studied using variational methods. Five crystal phases are obtained. As the layer spacing increases, the system will undergo a sequence of phase transitions. A common feature of most...
1995-03-01
2016-08-31
[ "cond-mat" ]
S. Narasimhan and Tin-Lun Ho
cond-mat/9503008
The Broken Symmetry of Two-Component $\nu=1/2$ Quantum Hall States
We show that the recently discovered $\nu=1/2$ quantum Hall states in bilayer systems are triplet p-wave pairing states of composite Fermions, of exactly the same form as $^{3}$He superfluids. The observed persistence (though weakening) of the $\nu=1/2$ state in the two- to one-component crossover region corresponds to...
1995-03-01
2016-08-31
[ "cond-mat" ]
Tin-Lun Ho
cond-mat/9503006
Kondo Insulators Modeled by the One Dimensional Anderson Lattice: A Numerical Renormalization Group Study
In order to better understand Kondo insulators, we have studied both the symmetric and asymmetric Anderson lattices at half-filling in one dimension using the density matrix formulation of the numerical renormalization group. We have calculated the charge gap, spin gap and quasiparticle gap as a function of the repulsi...
1995-03-01
2016-08-31
[ "cond-mat" ]
M. Guerrero and Clare C. Yu (Univ. of California, Irvine)
cond-mat/9503001
Single layer/bilayer transition of electron systems in AlGaAs/GaAs/AlGaAs quantum wells subject to in-plane magnetic fields
Equilibrium properties of electrons in double-heterojunction AlGaAs/GaAs\AlGaAs structures are investigated theoretically, using a full self-consistent numerical method. The transition from single to bilayer electron systems is discussed for the case of double-junction structures with varying distance between interface...
1995-03-01
2016-08-31
[ "cond-mat" ]
L. Smrcka, T. Jungwirth
cond-mat/9503005
Quantum Hall effect in spin-degenerate Landau levels: Spin-orbit enhancement of the conductivity
The quantum Hall regime in a smooth random potential is considered when two disorder-broadened Zeeman levels overlap strongly. Spin-orbit coupling is found to cause a drastic change in the percolation network which leads to a strong enhancement of the dissipative conductivity at finite temperature, provided the Fermi l...
1995-03-01
2016-08-31
[ "cond-mat" ]
D. G. Polyakov and M. E. Raikh
cond-mat/9503004
Crossover from BCS to Composite Boson (Local Pair) Superconductivity in Quasi-2D systems
The crossover from cooperative Cooper pairing to independent bound state (composite bosons) formation and condensation in quasi-2D systems is studied. It is shown that at low carrier density the critical superconducting temperature is equal to the temperature of Bose-condensation of ideal quasi-2D Bose-gas with heavy d...
1995-03-01
2015-06-25
[ "cond-mat", "supr-con" ]
E.V. Gorbar, V.M. Loktev and S.G. Sharapov
cond-mat/9503009
Mean-Field Equations for Spin Models with Orthogonal Interaction Matrices
We study the metastable states in Ising spin models with orthogonal interaction matrices. We focus on three realizations of this model, the random case and two non-random cases, i.e.\ the fully-frustrated model on an infinite dimensional hypercube and the so-called sine-model. We use the mean-field (or {\sc tap}) equat...
1995-03-01
2009-10-28
[ "cond-mat" ]
Giorgio Parisi and Marc Potters
cond-mat/9503003
Near-Equilibrium Dynamics of Crystalline Interfaces with Long-Range Interactions in 1+1 Dimensional Systems
The dynamics of a one-dimensional crystalline interface model with long-range interactions is investigated. In the absence of randomness, the linear response mobility decreases to zero when the temperature approaches the roughening transition from above, in contrast to a finite jump at the critical point in the Kosterl...
1995-03-01
2016-08-31
[ "cond-mat" ]
Yan-Chr Tsai (University of Pennsylvania)
cond-mat/9502115
Enhanced Transmission Through Disordered Potential Barrier
Effect of weak disorder on tunneling through a potential barrier is studied analytically. A diagrammatic approach based on the specific behavior of subbarrier wave functions is developed. The problem is shown to be equivalent to that of tunneling through rectangular barriers with Gaussian distributed heights. The distr...
1995-02-28
2009-10-28
[ "cond-mat" ]
V. Freilikher, M. Pustilnik and I. Yurkevich
cond-mat/9502120
Critical Behaviour of Superfluid $^4$He in Aerogel
We report on Monte Carlo studies of the critical behaviour of superfluid $^4$He in the presence of quenched disorder with long-range fractal correlations. According to the heuristic argument by Harris, uncorrelated disorder is irrelevant when the specific heat critical exponent $\alpha$ is negative, which is the case f...
1995-02-28
2016-08-31
[ "cond-mat" ]
K. Moon and S. M. Girvin
cond-mat/9502118
Random Matrix Solution of a Polymer Collapse Model
A polymer folding model on the square lattice is constructed with attractive contact interactions of strength 1/c^2, 0<c<1. The corresponding model on a dynamical random lattice, with freely fluctuating co-ordination number at each vertex, is formulated as a random two-matrix model and an expression for the partition f...
1995-02-28
2016-08-31
[ "cond-mat", "hep-th" ]
S. Dalley
cond-mat/9503013
Scaling and Selection in Cellular Structures and Living Polymers
The dynamical behavior of two types of non-equilibrium systems is discussed: $(a)$ two-dimensional cellular structures, and $(b)$ living polymers. Simple models governing their evolution are introduced and steady state distributions (cell side in the case of cellular structures and length in the case of living polymers...
1995-02-28
2007-05-23
[ "cond-mat" ]
David Mukamel (Weizmann)
cond-mat/9502117
Resonant Tunneling and Coulomb Oscillations
The influence of quantum fluctuations on electron transport through small metallic islands with Coulomb blockade effects is studied beyond the perturbative regime. In tunnel junctions with low resistance higher order coherent processes and ``inelastic resonant tunneling'' become important. We present a path integral re...
1995-02-28
2016-08-31
[ "cond-mat" ]
J\"urgen K\"onig, Herbert Schoeller, and Gerd Sch\"on
cond-mat/9502119
COSMOLOGICAL EXPERIMENTS IN SUPERFLUIDS AND SUPERCONDUCTORS
Evolution of the order parameter in condensed matter analogues of cosmological phase transitions is discussed. It is shown that the density of the frozen-out topological defects is set by the competition between the quench rate -- the rate at which the phase transition is taking place -- and the relaxation rate of the ...
1995-02-28
2016-08-31
[ "cond-mat" ]
Wojciech H. Zurek
cond-mat/9502116
Enhanced Transmission Due to Disorder
The transmissivity of a one-dimensional random system that is periodic on average is studied. It is shown that the transmission coefficient for frequencies corresponding to a gap in the band structure of the average periodic system increases with increasing disorder while the disorder is weak enough. This property is s...
1995-02-28
2009-10-28
[ "cond-mat" ]
V. D. Freilikher, A. A. Maradudin, A. R. McGurn, B. A. Liansky, I. V. Yurkevich
cond-mat/9502110
The Nonlinear Meissner Effect in Unconventional Superconductors
We examine the long-wavelength current response in anisotropic superconductors and show how the field-dependence of the Meissner penetration length can be used to detect the structure of the order parameter. Nodes in the excitation gap lead to a nonlinear current-velocity constitutive equation at low temperatures which...
1995-02-27
2016-08-31
[ "cond-mat", "supr-con" ]
D. Xu, S. K. Yip and J.A. Sauls (Northwestern University)
cond-mat/9502113
Spin-Charge Separation in the $t-J$ Model: Magnetic and Transport Anomalies
A real spin-charge separation scheme is found based on a saddle-point state of the $t-J$ model. In the one-dimensional (1D) case, such a saddle-point reproduces the correct asymptotic correlations at the strong-coupling fixed-point of the model. In the two-dimensional (2D) case, the transverse gauge field confining spi...
1995-02-27
2009-10-28
[ "cond-mat" ]
Z.Y. Weng, D.N. Sheng, and C.S. Ting
cond-mat/9502112
Magnetocrystalline Anisotropy Energy of a Transition Metal Monolayer: A Non-perturbative Theory
The magnetocrystalline anisotropy energy $E_{anis}$ for a monolayer of Fe and Ni is determined using a fully convergent tight-binding calculation including $s$-$d$ hybridization. The spin-orbit interaction $\lambda_{so}$ is treated non-perturbatively. Remarkably, we find $E_{anis}\propto\lambda_{so}^2$ and important co...
1995-02-27
2016-08-31
[ "cond-mat", "mtrl-th" ]
T. H. Moos, W. H\"ubner, and K. H. Bennemann (Institute for Theoretical Physics, Freie Universit\"at Berlin)
cond-mat/9502111
Skyrmions in Higher Landau Levels
We calculate the energies of quasiparticles with large numbers of reversed spins (``skyrmions'') for odd integer filling factors 2k+1, k is greater than or equals 1. We find, in contrast with the known result for filling factor equals 1 (k = 0), that these quasiparticles always have higher energy than the fully polariz...
1995-02-27
2016-08-31
[ "cond-mat" ]
X.-G. Wu and S. L. Sondhi
cond-mat/9502109
Majorana Fermions, Exact Mapping between Quantum Impurity Fixed Points with four bulk Fermion species, and Solution of the ``Unitarity Puzzle''
Several Quantum Impurity problems with four flavors of bulk fermions have zero temperature fixed points that show non fermi liquid behavior. They include the two channel Kondo effect, the two impurity Kondo model, and the fixed point occurring in the four flavor Callan-Rubakov effect. We provide a unified description w...
1995-02-26
2016-08-31
[ "cond-mat", "hep-th" ]
Juan M. Maldacena and Andreas W.W. Ludwig
cond-mat/9502108
Hydrodynamics and Nonlocal Conductivities in Vortex States
A hydrodynamical description for vortex states in type II superconductors with no pinning is presented based on the time-dependent GL equation, and the nonlocal conductivities are examined in terms of Kubo formula. Typically, the nonlocal conductivities deviate from the usual vortex flow expressions as the nonlocality ...
1995-02-24
2016-08-31
[ "cond-mat" ]
Ryusuke Ikeda (Indiana University)
cond-mat/9502106
Quantum fluctuations in the spiral phase of the Hubbard model
We study the magnetic excitations in the spiral phase of the two--dimensional Hubbard model using a functional integral method. Spin waves are strongly renormalized and a line of near--zeros is observed in the spectrum around the spiral pitch $\pm{\bf Q}$. The possibility of disordered spiral states is examined by stud...
1995-02-24
2016-08-31
[ "cond-mat" ]
C. Zhou and H. J. Schulz
cond-mat/9502107
Fractal properties of relaxation clusters and phase transition in a stochastic sandpile automaton
We study numerically the spatial properties of relaxation clusters in a two dimensional sandpile automaton with dynamic rules depending stochastically on a parameter p, which models the effects of static friction. In the limiting cases p=1 and p=0 the model reduces to the critical height model and critical slope model,...
1995-02-24
2016-08-31
[ "cond-mat" ]
S. Luebeck (Theoretische Physik, University Duisburg Germany), K.D. Usadel (Theoretische Physik, University Duisburg Germany), B. Tadic (Jozef Stefan Institute, University of Ljubljana, Slovenia)
cond-mat/9502102
THE BIT GENERATOR AND TIME SERIES PREDICTION
Generation and prediction of time series is analyzed for the case of a Bit-Generator: a perceptron where in each time step the input units are shifted one bit to the right with the state of the leftmost input unit set equal to the output unit in the previous time step. The long-time dynamical behavior of the Bit-Genera...
1995-02-24
2016-08-31
[ "cond-mat" ]
E. Eisenstein, I. Kanter, D.A. Kessler (Bar Ilan University) and W. Kinzel ( Universitaet Wuerzburg )
cond-mat/9502104
Ferromagnetism in Hubbard Models: Low Density Route
Thirty years ago the Hubbard model was introduced by Gutzwiller, Hubbard and Kanamori with the main purpose of mimicking the ferromagnetism of transition metals. Soon after, Nagaoka and Thouless pointed out a basic mechanism for ferromagnetism in strongly correlated electron systems by studying the motion of a single h...
1995-02-24
2016-08-31
[ "cond-mat" ]
E. Mueller-Hartmann
cond-mat/9502101
Giant Shapiro Steps in Josephson Arrays: Analytical Results
We study two-dimensional frustrated Josephson arrays driven by a combined DC plus AC current. We propose {\it ansatz} solutions that are a generalization of the solutions obtained in the DC case by Marino and Halsey (PRB {\bf 50}, 6289 (1994)). Using these solutions we derive expressions for the Shapiro step widths for...
1995-02-24
2016-08-31
[ "cond-mat" ]
Italo Marino
cond-mat/9502103
Universal Diamagnetism of Charged Scalar Fields
We show that charged scalar fields are always diamagnetic, even in the presence of interactions and at finite temperatures. This generalises earlier work on the diamagnetism of charged spinless bosons to the case of infinite degrees of freedom.
1995-02-24
2016-08-31
[ "cond-mat", "hep-th" ]
Debnarayan Jana
cond-mat/9502105
Model for the thermal conductivity of a quasicrystalline alloy
We present a simple model for the observed temperature dependence of the thermal conductivity of AlPdMn (Chernikov et al, Phys.Rev.B vol.51, (1995),153). We account for the low temperature data, upto and including the plateau of the thermal conductivity, and discuss the similarities and the differences between the quas...
1995-02-24
2016-08-31
[ "cond-mat", "mtrl-th" ]
A. Jagannathan
cond-mat/9502100
THE SPIN-S BLUME-CAPEL RG FLOW DIAGRAM
Using the Finite Size Scaling Renormalisation Group we obtain the two-dimensional flow diagram of the Blume-Capel model, for S = 1 and S = 3/2. In the first case our results are similar to those of Mean Field Theory, which predicts the existence of first and second order transitions whith a tricritical point. In the se...
1995-02-23
2016-08-31
[ "cond-mat" ]
S. Moss de Oliveira, P.M.C. de Oliveira and F.C. Sa Barreto
cond-mat/9502095
Renormalization group analysis of electrons near a Van Hove singularity.
A model of interacting two dimensional electrons near a Van Hove singularity is studied, using renormalization group techniques. In hole doped systems, the chemical potential is found to be pinned near the singularity, when the electron-electron interactions are repulsive. The RG treatment of the leading divergences ap...
1995-02-23
2016-08-31
[ "cond-mat", "hep-th", "supr-con" ]
J. Gonzalez, F. Guinea and M. A. H. Vozmediano
cond-mat/9502096
A Variational Estimate of the Binding Energy of Charge-Transfer Excitons in the Cuprate Superconductors.
We present a variational estimate for the binding energy of a Frenkel exciton in the insulating cuprate superconductors. Starting from the three band Hubbard model we perform a canonical transformation to O($t^2$), where $t$ is the bare nearest neighbour copper-oxygen hopping integral. An effective Hamiltonian is then ...
1995-02-23
2016-08-31
[ "cond-mat" ]
C. Vermeulen and W. Barford
cond-mat/9502094
Anomalous scaling and spin-charge separation in coupled chains
We use a bosonization approach to show that the three dimensional Coulomb interaction in coupled metallic chains leads to a Luttinger liquid for vanishing inter-chain hopping $t_{\bot}$, and to a Fermi liquid for any finite $t_{\bot}$. However, for small $t_{\bot} \neq 0$ the Greens-function satisfies a homogeneity rel...
1995-02-23
2016-08-31
[ "cond-mat" ]
Peter Kopietz, Volker Meden, and Kurt Schoenhammer
cond-mat/9502093
Effects of Impurity Vertex Correction on NMR Coherence Peak in S-Wave Superconductors
We study the effects of non-magnetic impurity vertex correction on nuclear spin-lattice relaxation rate $1/{T_1} $ of conventional s-wave superconductors within the Eliashberg formalism. We obtain, with a self-consistent $t-$matrix treatment of impurity scatterings, the expressions for impurity vertex function and nucl...
1995-02-23
2016-08-31
[ "cond-mat" ]
Han-Yong Choi and E. J. Mele
cond-mat/9502097
The motion of holes on the triangular lattice: t-J model
The motion of holes on the triangular lattice is studied using the t-J model. Within the Born self-consistent approximation and the exact Lanczos diagonalization, the single hole physics is first analyzed. Then the spiral theory of Shraiman and Siggia is used to investigate the case of a finite density of holes.
1995-02-23
2016-08-31
[ "cond-mat" ]
Mohamed Azzouz and Thierry Dombre
cond-mat/9502099
Electron Depletion Due to Bias of a T-Shaped Field-Effect Transistor
A T-shaped field-effect transistor, made out of a pair of two-dimensional electron gases, is modeled and studied. A simple numerical model is developed to study the electron distribution vs. applied gate voltage for different gate lengths. The model is then improved to account for depletion and the width of the two-dim...
1995-02-23
2009-10-28
[ "cond-mat" ]
G. A. Georgakis and Qian Niu
cond-mat/9502098
Competition between electron-phonon attraction and weak Coulomb repulsion
The Holstein-Hubbard model is examined in the limit of infinite dimensions. Conventional folklore states that charge-density-wave (CDW) order is more strongly affected by Coulomb repulsion than superconducting order because of the pseudopotential effect. We find that both incommensurate CDW and superconducting phases a...
1995-02-23
2016-08-31
[ "cond-mat" ]
J. K. Freericks (Georgetown University) and Mark Jarrell (University of Cincinnati)
cond-mat/9502086
Resonances in Small Fermi Systems
The systematics of the size dependence of the resonant response of small metal particles and nuclei to incident electromagnetic radiation is studied. The known radius$^{-1}$ variation of the full width at half maximum (FWHM) in matrix-embedded metal particles is qualitatively accounted for by a quantum calculation of t...
1995-02-22
2016-08-31
[ "cond-mat", "nucl-th" ]
Mustansir Barma and R. S. Bhalerao
cond-mat/9502088
Functional Bosonization of Interacting Fermions in Arbitrary Dimensions
We bosonize the long-wavelength excitations of interacting fermions in arbitrary dimension by directly applying a suitable Hubbard-Stratonowich transformation to the Grassmannian generating functional of the fermionic correlation functions. With this technique we derive a surprisingly simple expression for the single-p...
1995-02-22
2016-08-31
[ "cond-mat" ]
Peter Kopietz, Kurt Schoenhammer
cond-mat/9502089
Bosonization of interacting fermions in arbitrary dimension beyond the Gaussian approximation
We use our recently developed functional bosonization approach to bosonize interacting fermions in arbitrary dimension $d$ beyond the Gaussian approximation. Even in $d=1$ the finite curvature of the energy dispersion at the Fermi surface gives rise to interactions between the bosons. In higher dimensions scattering pr...
1995-02-22
2016-08-31
[ "cond-mat" ]
Peter Kopietz, Joachim Hermisson and Kurt Schoenhammer
cond-mat/9502087
DOMAIN WALLS IN THE QUANTUM TRANSVERSE ISING MODEL
We discuss several problems concerning domain walls in the spin $S$ Ising model at zero temperature in a magnetic field, $H/(2S)$, applied in the $x$ direction. Some results are also given for the planar ($y$-$z$) model in a transverse field. We treat the quantum problem in one dimension by perturbation theory at small...
1995-02-22
2009-10-28
[ "cond-mat" ]
Malte Henkel, A. Brooks Harris and Marek Cieplak
cond-mat/9502090
Integrable models of coupled Heisenberg chains
We show that the solutions of the Yang--Baxter equation invariant under the action of the Yangian $Y(sl_2)$ lead to inhomogenous vertex models. Starting from a four dimensional representation of $Y(sl_2)$ we obtain an integrable family of coupled Heisenberg spin-$1\over2$ chains. Some thermodynamical properties of this...
1995-02-22
2009-10-28
[ "cond-mat" ]
Holger Frahm and Claus R"odenbeck
cond-mat/9502092
CRITICAL EXPONENTS OF THE 3D ANTIFERROMAGNETIC THREE-STATE POTTS MODEL USING THE COHERENT-ANOMALY METHOD
The antiferromagnetic three-state Potts model on the simple-cubic lattice is studied using the coherent-anomaly method (CAM). The CAM analysis provides the estimates for the critical exponents which indicate the XY universality class, namely $\alpha=-0.011 $, $\beta= 0.351 $, $\gamma= 1.309 $ and $\delta= 4.73 $. This ...
1995-02-22
2015-06-25
[ "cond-mat" ]
M. Kolesik and M. Suzuki
cond-mat/9502085
Propagating S=1/2 particles in S=1 Haldane gap systems
Inspired by the recent experiments on Y$_{2-x}$Ca$_x$BaNiO$_5$, (J. F. DiTusa {\it et al.}, Phys. Rev. Lett. 73, 1857 (1994)), we discuss the dispersion relation of the $s$=1/2 particles in the $s$=1 Heisenberg and VBS model in the limit of small hopping amplitudes. The effective $s$=1/2 edge spins mix with the spin of...
1995-02-22
2016-08-31
[ "cond-mat" ]
Karlo Penc and Hiroyuki Shiba
cond-mat/9502091
Ground-State Dynamical Correlation Functions: An Approach from Density Matrix Renormalization Group Method
A numerical approach to ground-state dynamical correlation functions from Density Matrix Renormalization Group (DMRG) is developed. Using sum rules, moments of a dynamic correlation function can be calculated with DMRG, and with the moments the dynamic correlation function can be obtained by the maximum entropy method....
1995-02-22
2016-08-31
[ "cond-mat" ]
Hanbin Pang, H. Akhlaghpour, and M. Jarrell
cond-mat/9502079
Mesoscopic Systems With Fixed Number of Electrons
In this paper, we study the physics of mesoscopic systems with noninteracting, but fixed number of electrons. From a technical point of view, this means a discussion of the differences between the canonical and the grand canonical ensemble (fixed versus fluctuating number of particles). Such a discussion is not trivial...
1995-02-21
2016-08-31
[ "cond-mat" ]
W. Lehle, A. Schmid
cond-mat/9502081
The Toulose limit of the Multi-Channel Kondo model.
We study the Toulouse limit of the multi-channel Kondo model defined as the limit of maximal anisotropy which can be achieved without changing the infrared behaviour of the model. It is shown that when the number of channels exceeds 2, the interactions do not vanish and the Toulouse limit remains a non-trivial field th...
1995-02-21
2016-08-31
[ "cond-mat" ]
A. M. Tsvelik,
cond-mat/9502082
Chiral Non-Fermi Liquids in 1-d
We study models of chiral interacting fermions by means of conformal and Bethe-Ansatz techniques, and determine their thermodynamic properties and asymptotic correlation functions. We identify a class of fixed points characterizing the infrared behavior of the models. They display {\it chirally stabilized} non Fermi-Li...
1995-02-21
2016-08-31
[ "cond-mat", "hep-th" ]
Natan Andrei, Michael R. Douglas and Andr\'es Jerez
cond-mat/9502084
MICROWAVE-INDUCED "SOMERSAULT EFFECT" IN FLOW OF JOSEPHSON CURRENT THROUGH A QUANTUM CONSTRICTION
We consider the supercurrent flow through gated mesoscopic semiconductor hetrostructures in which a two-dimensional normal constriction is confined between superconducting electrodes. We show that for these structures the Josephson current, carried by quantized electron modes, can be strongly affected by an electromagn...
1995-02-21
2016-08-31
[ "cond-mat" ]
L. Y. Gorelik, V. S. Shumeiko, R. I. Shekhter, G. Wendin, and M.~Jonson
cond-mat/9502080
RANDOM MATRIX THEORY APPROACH TO THE INTENSITY DISTRIBUTIONS OF WAVES PROPAGATING IN A RANDOM MEDIUM
Statistical properties of coherent radiation propagating in a quasi - 1D random media is studied in the framework of random matrix theory. Distribution functions for the total transmission coefficient and the angular transmission coefficient are obtained.
1995-02-21
2009-10-28
[ "cond-mat" ]
Eugene Kogan and Moshe Kaveh
cond-mat/9502083
Photoemission spectra of ${\rm Sr_2 Cu O_2 Cl_2}$: a theoretical analysis
Recent angle resolved photoemission (ARPES) results for the insulating cuprate ${\rm Sr_2 Cu O_2 Cl_2}$ have provided the first experimental data which can be directly compared to the (theoretically) well--studied problem of a single hole propagating in an antiferromagnet. The ARPES results reported a small bandwidth, ...
1995-02-21
2016-08-31
[ "cond-mat" ]
A. Nazarenko, K.J.E. Vos, S. Haas, E. Dagotto, and R.J. Gooding
cond-mat/9502078
SCATTERING INVOLVING PROMPT AND EQUILIBRATED COMPONENTS, INFORMATION THEORY, AND CHAOTIC QUANTUM DOTS
We propose an information-theoretic statistical model to describe the universal features of those chaotic scattering processes characterized by a prompt and an equilibrated component. The model, introduced in the past in nuclear physics, incorporates the average value of the scattering matrix to describe the prompt pro...
1995-02-20
2016-08-31
[ "cond-mat", "chao-dyn", "nlin.CD" ]
H.U. Baranger (AT&T Bell Labs) and P.A. Mello (UNAM, Mexico)
cond-mat/9502077
Equilibrium Current and Orbital Magnetization in a Quantum Hall Fluid
We present a general theory for the equilibrium current distribution in an interacting two-dimensional electron gas subjected to a perpendicular magnetic field, and confined by a potential that varies slowly on the scale of the magnetic length. The distribution is found to consist of strips or channels of current, whic...
1995-02-19
2016-08-31
[ "cond-mat" ]
Michael R. Geller and Giovanni Vignale
cond-mat/9502075
Full dynamical solution for a spherical spin-glass model
We present a detailed analysis for the Langevin dynamics of a spherical spin-glass model (the spherical Sherrington-Kirkpatrick model). All the spins in the system are coupled by pairs via a random interaction matrix taken from the Gaussian ensemble. One finds that for a general initial configuration the system never r...
1995-02-17
2016-08-31
[ "cond-mat" ]
Leticia F. Cugliandolo and David S. Dean
cond-mat/9502073
Susceptibility of the one-dimensional, dimerized Hubbard model
We show that the zero temperature susceptibility of the one-dimensional, dimerized Hubbard model at quarter-filling can be accurately determined on the basis of exact diagonalization of small clusters. The best procedure is to perform a finite-size scaling of the spin velocity $u_\sigma$, and to calculate the susceptib...
1995-02-17
2016-08-31
[ "cond-mat" ]
Frederic Mila and Karlo Penc
cond-mat/9502074
Deducing correlation parameters from optical conductivity in the Bechgaard salts
Numerical calculations of the kinetic energy of various extensions of the one-dimensional Hubbard model including dimerization and repulsion between nearest neighbours are reported. Using the sum rule that relates the kinetic energy to the integral of the optical conductivity, one can determine which parameters are con...
1995-02-17
2016-08-31
[ "cond-mat" ]
Frederic Mila
cond-mat/9502076
Bosonization rules in $1/2 +1$ dimensions
We derive the bosonization rules for free fermions on a half-line with physically sensible boundary conditions for Luttinger fermions. We use path-integral methods to calculate the bosonized fermionic currents on the half-line and derive their commutation relations for a system with a boundary. We compute the fermion d...
1995-02-17
2009-10-28
[ "cond-mat", "hep-th" ]
Manuel Fuentes, Ana Lopez, Eduardo Fradkin and Enrique Moreno
cond-mat/9502071
Four-Particle Anyon Exciton: Boson Approximation
A theory of anyon excitons consisting of a valence hole and three quasielectrons with electric charges $(-e/3)$ is presented. A full symmetry classification of the $k=0$ states is given, where $k$ is the exciton momentum. The energy levels of these states are expressed by quadratures of confluent hypergeometric functio...
1995-02-17
2016-08-08
[ "cond-mat" ]
M. E. Portnoi and E. I. Rashba
cond-mat/9502072
COMPLETE SOLUTION OF THE XXZ-MODEL ON FINITE RINGS. DYNAMICAL STRUCTURE FACTORS AT ZERO TEMPERATURE.
The finite size effects of the dynamical structure factors in the XXZ-model are studied in the euclidean time $(\tau)$-representation. Away from the critical momentum $p=\pi$ finite size effects turn out to be small except for the large $\tau$ limit. The large finite size effects at the critical momentum $p=\pi$ signal...
1995-02-17
2009-10-28
[ "cond-mat" ]
K. Fabricius, U. L\"ow and K.-H. M\"utter
cond-mat/9502070
Semiclassical Analysis of the Conductance of Mesoscopic Systems
The Kubo formula for the conductance of classically chaotic systems is analyzed semiclassically, yielding simple expressions for the mean and the variance of the quantum interference terms. In contrast to earlier work, here times longer than $O( \log \hbar^{-1} )$ give the dominant contributions, i.e. the limit $\hbar ...
1995-02-16
2016-08-31
[ "cond-mat", "chao-dyn", "nlin.CD" ]
Nathan Argaman (Weizmann Institute, now at ITP, UCSB)
cond-mat/9502114
Defects in Superfluids, Superconductors and Membranes
An introduction to the defects which dominate the physics of superfluid He$^4$ films, of superconducting slabs and of crystalline and hexatic membranes is given. We first review point vortices in two-dimensional neutral superfluids and discuss the unusual screening which arises when the bosons are charged, as in superc...
1995-02-16
2007-05-23
[ "cond-mat" ]
David R. Nelson (Harvard University)
cond-mat/9502067
Replica Theory and Large D Josephson Junction Hypercubic Models
We study the statistical mechanics of a $D$-dimensional array of Josephson junctions in presence of a magnetic field on a lattice of side $2$. In the high temperature region the thermodynamical properties can be computed in the limit $D \to \infty$. A conjectural form of the thermodynamic properties in the low temperat...
1995-02-16
2016-08-31
[ "cond-mat", "hep-lat", "hep-th" ]
Enzo Marinari, Giorgio Parisi and Felix Ritort
cond-mat/9502069
Early stage scaling in phase ordering kinetics
A global analysis of the scaling behaviour of a system with a scalar order parameter quenched to zero temperature is obtained by numerical simulation of the Ginzburg-Landau equation with conserved and non conserved order parameter. A rich structure emerges, characterized by early and asymptotic scaling regimes, separat...
1995-02-16
2016-08-31
[ "cond-mat" ]
F.Corberi, A.Coniglio and M.Zannetti