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cond-mat/9506096
A Model for High Temperature Superconductors using the Extended Hubbard Model
We derive a method to study the phase diagram for high temperature superconductors (HTCS). Our starting point is the Hubbard Hamiltonian with a weak attractive interaction to obtain the formation of bound pairs. We consider this attractive potential at different positions for different compounds accordingly to the expe...
1995-06-21
2009-10-28
[ "cond-mat" ]
Evandro V.L.de Mello
cond-mat/9506095
On a Network Model of Localization in a Random Magnetic Field
We consider a network model of snake states to study the localization problem of non-interacting fermions in a random magnetic field with zero average. After averaging over the randomness, the network of snake states is mapped onto $M$ coupled SU$(2N)$ spin chains in the $N \rightarrow 0$ limit. The number of snake sta...
1995-06-21
2009-10-28
[ "cond-mat" ]
Yong Baek Kim, Akira Furusaki, Derek K. K. Lee
cond-mat/9506094
Spin-Charge Separated Luttinger Liquid in Arbitrary Spatial Dimensions
A model with a singular forward scattering amplitude for particles with opposite spins in d spatial dimensions is proposed and solved by using the bosonization transformation. This interacting potential leads to the spin-charge separation. Thermal properties at low temperature for this Luttinger liquid are discussed. A...
1995-06-21
2009-10-28
[ "cond-mat", "supr-con" ]
Krzysztof Byczuk and Jozef Spalek
cond-mat/9506090
Diagrammatic evaluation of conformal weights in the U_q[SU(2)] symmetric Heisenberg chain
We consider the $U_q[SU(2)]$ symmetric Heisenberg chain when $q=e^{i\pi/(m+1)}$ and $m$ is integer. We consider the cases $m=3$ and $m=5$ which correspond to the Ising and 3-state Potts models. We study the finite size scaling (FSS) of the ground states in different quantum spin sectors and restricting to highest weigh...
1995-06-20
2007-05-23
[ "cond-mat", "hep-lat" ]
Matteo Beccaria
cond-mat/9506087
Universal Finite-Size Scaling Function of the Ferromagnetic Heisenberg Chain in a Magnetic Field. II
The finite-size scaling function of the nonlinear susceptibility of the ferromagnetic Heisenberg chain is given explicitly. It is conjectured that the scaling function is universal for any values of $S$. The conjecture is based on the exact solution of the nonlinear susceptibility for $S=\infty$, and numerical calculat...
1995-06-20
2009-10-28
[ "cond-mat" ]
Hiroaki Nakamura, Naomichi Hatano and Minoru Takahashi (Institute for Solid State Physics, University of Tokyo, Department of Physics, University of Tokyo and Department of Physics, Harvard University)
cond-mat/9506091
Scaling properties of driven interfaces in disordered media
We perform a systematic study of several models that have been proposed for the purpose of understanding the motion of driven interfaces in disordered media. We identify two distinct universality classes: (i) One of these, referred to as directed percolation depinning (DPD), can be described by a Langevin equation simi...
1995-06-20
2009-10-28
[ "cond-mat" ]
L.A.N. Amaral, A.-L. Barabasi, H.A. Makse, and H.E. Stanley (Center for Polymer Studies and Dept. of Physics, Boston University)
cond-mat/9506088
On the Bilayer Coupling in the Yttrium-Barium Family of High Temperature Superconductors
We present and solve a model for the susceptibility of two CuO2 planes coupled by an interplane coupling J_perp and use the results to analyze a recent "cross-relaxation" NMR experiment on Y2Ba4Cu7O15. We deduce that in this material the product of J_perp and the maximum value of the in-plane susceptibility chi_max var...
1995-06-20
2007-05-23
[ "cond-mat" ]
A. J. Millis (AT&T Bell Laboratories) and H. Monien (ETH Zuerich)
cond-mat/9506081
Zero-bias anomalies and boson-assisted tunneling through quantum dots
We study resonant tunneling through a quantum dot with one degenerate level in the presence of a strong Coulomb repulsion and a bosonic environment. Using a real-time approach we calculate the spectral density and the nonlinear current within a conserving approximation. The spectral density shows a multiplet of Kondo p...
1995-06-19
2009-10-28
[ "cond-mat" ]
J\"urgen K\"onig, Herbert Schoeller and Gerd Sch\"on
cond-mat/9506080
The H-Boltzmann's Theorem for Magnetic Systems
In a time-reversal non-invariant system the entropy production, dS/dt, may be negative. Close to the critical point of medium it is positive: larger or smaller as compared with one above critical point depending on whether the transitions from lower states to higher states of the system are more (less) probable than th...
1995-06-19
2007-05-23
[ "cond-mat" ]
S. Malinowski
cond-mat/9506085
Quantum Breathing Mode for Electrons with 1/r^2 Interaction
We discuss a collective "breathing" mode of electrons with inverse-square-law interactions in a two-dimensional quantum dot and a perpendicular magnetic field.
1995-06-19
2009-10-28
[ "cond-mat" ]
Michael R. Geller and Giovanni Vignale
cond-mat/9506082
Two phase transitions in the fully frustrated $XY$ model
The fully frustrated $XY$ model on a square lattice is studied by means of Monte Carlo simulations. A Kosterlitz-Thouless transition is found at $T_{\rm KT} \approx 0.446$, followed by an ordinary Ising transition at a slightly higher temperature, $T_c \approx 0.452$. The non-Ising exponents reported by others, are exp...
1995-06-19
2009-10-28
[ "cond-mat" ]
Peter Olsson
cond-mat/9506089
Revisiting Thouless conductance formula
It was shown using perturbation theory[1] that Thouless energy Ec for a quantum system scales linearly with the conductance of the system. We derive in an alternate way in 1-D that Ec scales with the conductance in a very different way. We physically show the difference between our approach and that of ref. 1 to expect...
1995-06-19
2008-02-03
[ "cond-mat" ]
P. Singha Deo
cond-mat/9506084
Collapse of Spin-Splitting in the Quantum Hall Effect
It is known experimentally that at not very large filling factors $\nu$ the quantum Hall conductivity peaks corresponding to the same Landau level number $N$ and two different spin orientations are well separated. These peaks occur at half-integer filling factors $\nu = 2 N + 1/2$ and $\nu = 2 N + 3/2$ so that the dist...
1995-06-19
2009-10-28
[ "cond-mat" ]
M.M.Fogler and B.I.Shklovskii (University of Minnesota)
cond-mat/9506077
A note on inverse-square exchange models
The su(1$|$1) symmetric version of the Haldane-Shastry spin chain is diagonalized by means of a linear transformation. The same transformation applied to the original su(2) model yields simple expressions for the Hamiltonian and the generators of the Yangian symmetry of the model in terms of spin wave operators.
1995-06-19
2016-08-15
[ "cond-mat", "hep-th" ]
Frank G\"ohmann and Miki Wadati
cond-mat/9506083
Influence of next-nearest-neighbor electron hopping on the static and dynamical properties of the 2D Hubbard model
Comparing experimental data for high temperature cuprate superconductors with numerical results for electronic models, it is becoming apparent that a hopping along the plaquette diagonals has to be included to obtain a quantitative agreement. According to recent estimations the value of the diagonal hopping $t'$ appear...
1995-06-19
2009-10-28
[ "cond-mat" ]
Daniel Duffy and Adriana Moreo (Florida State University)
cond-mat/9506078
Variational Monte Carlo Studies of t-J-type Models
We give a brief review of recent developments by the variational Monte Carlo method, in addition to some new results. We discuss $t$-$J$-type models: the ordinary $t$-$J$ model in one and two dimensions, and the one-dimensional supersymmetric $t$-$J$ model with the long-range coupling of inverse square.
1995-06-19
2007-05-23
[ "cond-mat" ]
Hisatoshi Yokoyama, Yoshio Kuramoto and Masao Ogata
cond-mat/9506086
Adaptive coordinate, real-space electronic structure calculations on parallel computers
We present a method for electronic structure calculations that retains all of the advantages of real space and addresses the inherent inefficiency of a regular grid, which has equal precision everywhere. The computations are carried out on a {\em regular} mesh in {\em curvilinear space}, which allows natural and effici...
1995-06-19
2009-10-28
[ "cond-mat", "mtrl-th" ]
Gil Zumbach, N. A. Modine and Efthimios Kaxiras (Department of Physics, Harvard University)
cond-mat/9506079
Wave functions for arbitrarily Polarized Quantum Hall States
We determine the wave functions for arbitrarily polarized quantum Hall states by employing the doublet model which has been proposed recently to describe arbitrarily polarized quantum Hall states. Our findings recover the well known fully polarized Laughlin wave functions and unpolarized Halperin wave function for the ...
1995-06-18
2008-02-03
[ "cond-mat" ]
Sudhansu S. Mandal and V. Ravishankar
cond-mat/9506075
Cluster Algorithms For Anisotropic Quantum Spin Models
We present cluster Monte Carlo algorithms for the $XYZ$ quantum spin models. In the special case of $S=1/2$, the new algorithm can be viewed as a cluster algorithm for the 8-vertex model. As an example, we study the $S=1/2$ $XY$ model in two dimensions with a representation in which the quantization axis lies in the ea...
1995-06-18
2009-10-28
[ "cond-mat" ]
N. Kawashima
cond-mat/9506076
Magnetic anisotropies and general on--site Coulomb interactions in the cuprates
This paper derives the anisotropic superexchange interactions from a Hubbard model for excitations within the copper 3d band and the oxygen 2p band of the undoped insulating cuprates. We extend the recent calculation of Yildirim et al. [Phys. Rev. B {\bf VV}, pp, 1995] in order to include the most general on--site Coul...
1995-06-18
2009-10-28
[ "cond-mat" ]
O. Entin-Wohlman, A. B. Harris, and Amnon Aharony
cond-mat/9506073
Broken ergodicity and glassy behavior in a deterministic chaotic map
A network of $N$ elements is studied in terms of a deterministic globally coupled map which can be chaotic. There exists a range of values for the parameters of the map where the number of different macroscopic configurations is very large, and there is violation of selfaveraging. The time averages of functions, which ...
1995-06-16
2009-10-28
[ "cond-mat" ]
A. Crisanti, M. Falcioni, A. Vulpiani
cond-mat/9506072
Critical level spacing distribution of two-dimensional disordered systems with spin-orbit coupling
The energy level statistics of 2D electrons with spin-orbit scattering are considered near the disorder induced metal-insulator transition. Using the Ando model, the nearest-level-spacing distribution is calculated numerically at the critical point. It is shown that the critical spacing distribution is size independent...
1995-06-16
2009-10-28
[ "cond-mat" ]
L. Schweitzer and I. Kh. Zharekeshev
cond-mat/9506074
The Upper Critical Field for Unconventional Superconducting Film: a Kink due to the Boundary Conditions
Boundary conditions for unconventional superconducting order parameter are obtained on the basis of a microscopic theory. The upper critical field in a superconducting film is examined for unconventional superconductors with two-component order parameter and is compared with the case of accidental degeneracy. It is sho...
1995-06-16
2009-10-28
[ "cond-mat" ]
Yu.S.Barash, A.V.Galaktionov, and A.A.Svidzinsky
cond-mat/9506068
Finite Temperature Resonant Magnetotunneling in AlGaAs-GaAs-AlGaAs Heterostructures
We have analyzed the effect of electron-LO phonon interaction in a double-barrier resonant tunneling structure under a magnetic field {\bf B} applied parallel to the tunneling current. While the low temperature anti-crossing phenomenon has already been investigated, here we study the phonon absorption resonant magnetot...
1995-06-15
2007-05-23
[ "cond-mat" ]
Oe. Lund Boe, Yu. Galperin, and K.A. Chao
cond-mat/9506066
Topological orders and Edge excitations in FQH states
Fractional quantum Hall (FQH) liquids contain extremely rich internal structures which represent a whole new kind of ordering. We discuss characterization and classification of the new orders (which is called topological orders). We also discuss the edge excitations in FQH liquids, which form the so-called chiral Lutti...
1995-06-15
2009-10-28
[ "cond-mat" ]
Xiao-Gang Wen (MIT)
cond-mat/9506065
Theory of Underdoped Cuprates
We develop a slave-boson theory for the t-J model at finite doping which respects an SU(2) symmetry -- a symmetry previously known to be important at half filling. The mean field phase diagram is found to be consistent with the phases observed in the cuprate superconductors, which contains d-wave superconductor, spin g...
1995-06-15
2009-10-28
[ "cond-mat" ]
Xiao-Gang Wen, and Patrick A. Lee
cond-mat/9506060
Renormalization Group transformations of the decimation type in more than one dimension
We develop a formalism for performing real space renormalization group transformations of the "decimation type" using low temperature perturbation theory. This type of transformations beyond $d=1$ is highly nontrivial even for free theories. We construct such a solution in arbitrary dimensions and develop a weak coupli...
1995-06-15
2016-08-31
[ "cond-mat", "hep-lat" ]
V. Kushnir and B. Rosenstein
cond-mat/9506069
Multifractal properties of critical eigenstates in two-dimensional systems with symplectic symmetry
The multifractal properties of electronic eigenstates at the metal-insulator transition of a two-dimensional disordered tight-binding model with spin-orbit interaction are investigated numerically. The correlation dimensions of the spectral measure $\widetilde{D}_{2}$ and of the fractal eigenstate $D_{2}$ are calculate...
1995-06-15
2009-10-28
[ "cond-mat" ]
Ludwig Schweitzer
cond-mat/9506070
Marshall sign and the doped $t-J$ model
Marshall sign as a sole source of sign problem hidden in an antiferromagnet is explored under doping. By tracking the Marshall sign, a zero spectral weight $Z$ is revealed in the doped antiferromagnetic system. $Z=0$ is caused by a phase string induced by the ``bare'' hole. By eliminating such a phase string through no...
1995-06-15
2007-05-23
[ "cond-mat" ]
Z.Y. Weng, D.N. Sheng, and Y.C. Chen
cond-mat/9506067
Adsorption of colloidal particles in the presence of external field
We present a new class of sequential adsorption models in which the adsorbing particles reach the surface following an inclined direction (shadow models). Capillary electrophoresis, adsorption in the presence of a shear or on an inclined substrate are physical manifestations of these models. Numerical simulations are c...
1995-06-15
2009-10-28
[ "cond-mat" ]
I. Pagonabarraga, J. Bafaluy and J. M. Rubi
cond-mat/9506061
Nontopological thermal solitons in isotropic ferromagnetic lattices
The paper deals with the properties of thermally excited solitons of the isotropic spin-$S$ ferromagnetic chain with nearest-neighbor logarithmic interactions. The exact statistical mechanics of the interacting soliton gas is developed for the general case (arbitrary $S$, temperature and magnetic field). At low tempera...
1995-06-14
2007-06-19
[ "cond-mat" ]
N. Theodorakopoulos (Theor. and Phys. Chem. Inst., Nat'l Hell. Res. Found., Athens, Greece)
cond-mat/9506058
Atomic beam correlations and the quantum state of the micromaser
Correlation measurements on the states of two-level atoms having passed through a micromaser at different times can be used to infer properties of the quantum state of the radiation field in the cavity. Long(short) correlation length in time is to some extent associated with super(sub)-Poissonian photon statistics. The...
1995-06-14
2008-02-03
[ "cond-mat" ]
Per Elmfors, Benny Lautrup and Bo-Sture Skagerstam
cond-mat/9506062
Vortex Pair Production and Decay of a 2-D Supercurrent by a Quantum Field Theory Approach
We investigate the phenomenon of the decay of a supercurrent through homogeneous nucleation of vortex-antivortex pairs in a 2-D like superconductor or superfluid by means of a quantum electrodynamics formulation for the decay of the 2-D vacuum. The case in which both externally-driven current and Magnus force are prese...
1995-06-14
2009-10-28
[ "cond-mat" ]
Roberto Iengo and Giancarlo Jug (SISSA and Universita' di Milano)
cond-mat/9506063
Spectral Correlations from the Metal to the Mobility Edge
We have studied numerically the spectral correlations in a metallic phase and at the metal-insulator transition. We have calculated directly the two-point correlation function of the density of states $R(s,s')$. In the metallic phase, it is well described by the Random Matrix Theory (RMT). For the first time, we also f...
1995-06-14
2009-10-28
[ "cond-mat" ]
D. Braun and G. Montambaux
cond-mat/9506059
Supercurrent States in 1D Finite-Size Rings
We consider topological supercurrent excitations (SC) in 1D mesoscopic rings. Under certain conditions such excitations are well-defined except for (i) a tunneling between resonating states with clockwise and anti-clockwise currents, which may be characterized by the amplitude $\Delta$, and (ii) a decay of SC assisted ...
1995-06-14
2016-08-31
[ "cond-mat" ]
V.A.Kashurnikov, A.I.Podlivaev, N.V.Prokof'ev, B.V.Svistunov
cond-mat/9506064
Odd Parity and Line Nodes in Heavy Fermion Superconductors
Group theory arguments have demonstrated that a general odd parity order parameter cannot have line nodes in the presence of spin-orbit coupling. In this paper, it is shown that these arguments do not hold on the $k_z = \pi/c$ zone face of a hexagonal close packed lattice. In particular, three of the six odd parity rep...
1995-06-14
2009-10-28
[ "cond-mat", "supr-con" ]
M. R. Norman
cond-mat/9506053
Persistent Currents for Interacting Electrons: a Simple Hartree-Fock Picture
The average persistent current <I> of diffusive electrons in the Hartree-Fock approximation is derived in a simple non-diagrammatic picture. The Fourier expansion directly reflects the winding number decomposition of the diffusive motion around the ring. One recovers the results of Ambegaokar and Eckern, and Schmid. Mo...
1995-06-13
2009-10-28
[ "cond-mat" ]
Gilles Montambaux
cond-mat/9506054
A mean-field hard-spheres model of glass
We present a model of spheres moving in a high-dimensional compact space. We relate it to a mixed matrix model with a $O(N)$ invariant model plus a $P(N)$ invariant perturbation. We then study the low pressure regime by performing a diagrammatic expansion of this matrix model. Finally, we show the results from numerica...
1995-06-13
2009-10-28
[ "cond-mat", "hep-th" ]
Leticia F. Cugliandolo, J. Kurchan, Remi Monasson and Giorgio Parisi
cond-mat/9506055
Dynamical Properties of Quantum Hall Edge States
We consider the dynamical properties of simple edge states in integer ($\nu = 1$) and fractional ($ \nu = 1/2m+1$) quantum Hall (QH) liquids. The influence of a time-dependent local perturbation on the ground state is investigated. It is shown that the orthogonality catastrophe occurs for the initial and final state ov...
1995-06-13
2009-10-28
[ "cond-mat" ]
A.V.Balatsky(Los Alamos and Landau Institute) and S.I.Matveenko(Landau Institute and Los Alamos)
cond-mat/9506056
Slow cooling dynamics of the Ising $p$-spin interaction spin-glass model
We have studied dynamical behaviour of the infinite-range Ising spin glass model with $p$-spin interaction above and below the transition into the non-ergodic phase. The transition is continuous at sufficiently high external magnetic field. The dynamic critical exponent of the power-law decay of the autocorrelation fun...
1995-06-13
2007-05-23
[ "cond-mat" ]
D. M. Kagan, M. V. Feigelman
cond-mat/9506057
Exact effective action for fermions in one dimension with backscattering at a boundary
We report exact results for the partition function for free Dirac fermions on a half line with physically sensible boundary conditions. An exact effective action for general backscattering amplitudes is derived. The action also includes the effects of both a (time-dependent) forward scattering amplitude and a dynamical...
1995-06-13
2009-10-28
[ "cond-mat", "hep-th" ]
Manuel Fuentes, Ana Lopez and Eduardo Fradkin
cond-mat/9506049
On the number of metastable states in spin glasses
In this letter, we show that the formulae of Bray and Moore for the average logarithm of the number of metastable states in spin glasses can be obtained by calculating the partition function with $m$ coupled replicas with the symmetry among these explicitly broken according to a generalization of the `two-group' ansatz...
1995-06-12
2009-10-28
[ "cond-mat" ]
Giorgio Parisi and Marc Potters
cond-mat/9506051
Fermi Liquid - Non-Fermi Liquid Transition in the Double Exchange Model
Motivated by recent discovery of colossal magnetoresistance in La$_(1-x)$Ca$x$MnO$_3$ and other manganites, we have studied the double exchange model. We argue that the forced alignment of conduction-electron spin with the core spins that causes ferromagnetism also projects out a large part of the Hilbert space needed ...
1995-06-12
2007-05-23
[ "cond-mat" ]
Sanjoy K. Sarker
cond-mat/9506052
Scaling Theory of Antiferromagnetic Heisenberg Ladder Models
The $S=1/2$ antiferromagnetic Heisenberg model on multi-leg ladders is investigated. Criticality of the ground-state transition is explored by means of finite-size scaling. The ladders with an even number of legs and those with an odd number of legs are distinguished clearly. In the former, the energy gap opens up as $...
1995-06-12
2016-08-31
[ "cond-mat" ]
Naomichi Hatano and Yoshihiro Nishiyama (University of Tokyo)
cond-mat/9506071
Theory of arbitrarily polarized quantum Hall states
We propose a global model which accounts for all the observed quantum Hall states in terms of an abelian doublet of Chern-Simons gauge fields, with the strength of the Chern-Simons term given by a coupling matrix. The model is employed within the composite fermion picture.
1995-06-12
2008-02-03
[ "cond-mat", "hep-th" ]
Sudhansu S. Mandal and V. Ravishankar
cond-mat/9506050
Non-equilibrium Dynamics Following a Quench to the Critical Point in a Semi-infinite System
We study the non-equilibrium dynamics (purely dissipative and relaxational) in a semi-infinite system following a quench from the high temperature disordered phase to its critical temperature. We show that the local autocorrelation near the surface of a semi-infinite system decays algebraically in time with a new expon...
1995-06-12
2009-10-28
[ "cond-mat" ]
Satya N. Majumdar and Anirvan M. Sengupta
cond-mat/9506048
Self organized criticality in a sandpile model with threshold dissipation
We study a nonconservative sandpile model in one dimension, in which, if the height at any site exceeds a threshold value, the site topples by transferring one particle along each bond connecting it to its neighbours. Its height is then set to one, irrespective of the initial value. The model shows nontrivial critical ...
1995-06-12
2016-08-31
[ "cond-mat" ]
Agha Afsar Ali
cond-mat/9506047
Stability of Matter in Magnetic Fields
In the presence of arbitrarily large magnetic fields, matter composed of electrons and nuclei was known to be unstable if $\alpha$ or $Z$ is too large. Here we prove that matter {\it is stable\/} if $\alpha<0.06$ and $Z\alpha^2<0.04$.
1995-06-11
2009-10-28
[ "cond-mat", "hep-th" ]
Elliott Lieb, Michael Loss and Jan Philip Solovej
cond-mat/9506046
Global phase diagram for the quantum Hall effect: An experimental picture
We study the behavior of the extended states of a two-dimensional electron system in silicon in a magnetic field, B. Our results show that the extended states, corresponding to the centers of different Landau levels, merge with the lowest extended state as B --> 0. Using our data, we construct an experimental-based ``d...
1995-06-10
2016-08-31
[ "cond-mat" ]
S. V. Kravchenko, Whitney Mason, J. E. Furneaux, and V. M. Pudalov
cond-mat/9506045
Ultrasonic attenuation in d-wave superconductors
The longitudinal ultrasonic attenuation at low temperatures for a $d$-wave superconducting order parameter is examined. The ratio of the superconducting to normal state attenuation, $\alpha_{s}/\alpha_{n}$, depends strongly on the direction of propagation of ultrasound with maxima corresponding to nodes of the order pa...
1995-06-10
2007-05-23
[ "cond-mat" ]
Vladimir N. Kostur, Jayanta K. Bhattacharjee, and Richard A. Ferrell
cond-mat/9506041
The Ba 4d-f giant dipole resonance as a probe of the structure of endohedral Ba@C_n metallofullerenes
We calculate the x-ray absorption near edge structure (XANES) modulating the Ba 4d-photoabsorption cross section - the giant dipole resonance - centered around 110 eV photon energy for several models of spherical and non-spherical Ba@C_n metallofullerene cage systems. In the cases considered, the XANES interference pat...
1995-06-09
2009-10-28
[ "cond-mat" ]
Jarek Luberek and Goran Wendin (Department of Applied Physics, Chalmers University of Technology)
cond-mat/9506039
Transport Properties of "Extended-s" State Superconductors
Superconducting states with "extended s-wave" symmetry have been suggested in connection with recent ARPES experiments on BSCCO. In the presence of impurities, thermodynamic properties of such states reflect a residual density of states $N(0)$ for a range of concentrations. While properties reflecting $N(\omega)$ alone...
1995-06-09
2009-10-28
[ "cond-mat" ]
L.S. Borkowski, P.J. Hirschfeld, and W.O. Putikka
cond-mat/9506044
Design of Copolymeric Materials
We devise a method for designing materials that will have some desired structural characteristics. We apply it to multiblock copolymers that have two different types of monomers, A and B. We show how to determine what sequence of A's and B's should be synthesised in order to give a particular structure and morphology. ...
1995-06-09
2009-10-28
[ "cond-mat" ]
Tanya Kurosky and J.M.Deutsch
cond-mat/9506042
Lifetime of Two-Dimensional Electrons Measured by Tunneling Spectroscopy
For electrons tunneling between parallel two-dimensional electron systems, conservation of in-plane momentum produces sharply resonant current-voltage characteristics and provides a uniquely sensitive probe of the underlying electronic spectral functions. We report here the application of this technique to accurate mea...
1995-06-09
2009-10-28
[ "cond-mat" ]
S.Q. Murphy, J.P. Eisenstein, L.N. Pfeiffer and K.W. West
cond-mat/9506043
Heavy Fermion Superconductivity
A brief review is given on the current state of experimental and theoretical work in the field of heavy fermion superconductivity. Particular emphasis is placed on those experiments which demonstrate the presence of an unconventional order parameter, as well as the intricate interplay of magnetism and superconductivity...
1995-06-09
2008-02-03
[ "cond-mat", "supr-con" ]
Robert H. Heffner and Michael R. Norman
cond-mat/9506040
Angular Dependent Magnetoresistance Oscillation of a Quasi-Two-Dimensional System in a Periodic Potential
(BEDT-TTF)$_2$MHg(SCN)$_4$[M:K,Rb,Tl] shows typical two-dimensional angular dependent magnetoresistance oscillation (ADMRO) at high temperature (T$>$8K), but at lower temperature it shows anomalously large magnetoresistance, and the ADMRO pattern changes. These low temperature behaviors are explained as effects of a pe...
1995-06-09
2009-10-28
[ "cond-mat" ]
Daijiro Yoshioka
cond-mat/9506034
Aggregation with Multiple Conservation Laws
Aggregation processes with an arbitrary number of conserved quantities are investigated. On the mean-field level, an exact solution for the size distribution is obtained. The asymptotic form of this solution exhibits nontrivial ``double'' scaling. While processes with one conserved quantity are governed by a single sca...
1995-06-08
2009-10-28
[ "cond-mat" ]
P.L. Krapivsky and E. Ben-Naim
cond-mat/9506038
Low lying excitations of the Dynamical Jahn-Teller ions C_60^- and C_60^2-
We compute the vibronic spectrum of gas phase fullerene negative ions C_{60}^{-} and C_{60}^{2-}. We treat accurately the linear dynamical Jahn-Teller of these ions in their ground state. In particular, coupling of the t_{1u} orbital to the eight H_g vibrational modes is handled by exact diagonalizations including up t...
1995-06-08
2012-10-29
[ "cond-mat" ]
Nicola Manini and Erio Tosatti
cond-mat/9506035
Density-functional theory of quantum wires and dots in a strong magnetic field
We study the competition between the exchange and the direct Coulomb interaction near the edge of a two-dimensional electron gas in a strong magnetic field using density-functional theory in a local approximation for the exchange-energy functional. Exchange is shown to play a significant role in reducing the spatial ex...
1995-06-08
2009-10-28
[ "cond-mat" ]
T.H. Stoof and Gerrit E.W. Bauer
cond-mat/9506037
Crystal surfaces with correlated disorder: Phase transitions between roughening and superroughening
A theory for surface transitions in the presence of a disordered pinning potential is presented. Arbitrary disorder correlations are treated in the framework of a dynamical functional renormalization group. The roughening transition, where surface roughness and mobility behave discontinuously, is shown to turn smoothly...
1995-06-08
2009-10-28
[ "cond-mat" ]
Stefan Scheidl (Univ. Cologne, Germany)
cond-mat/9506036
Time-dependent resonant tunneling via two discrete states
We theoretically investigate time-dependent resonant tunneling via two discrete states in an experimentally relevant setup. Our results show that the dc transport through the system can be controled by applying irradiation with a frequency which matches the energy difference between the discrete states. We predict reso...
1995-06-08
2009-10-28
[ "cond-mat" ]
T.H. Stoof and Yu.V. Nazarov
cond-mat/9506027
ON A DYNAMICAL MODEL OF GLASSES
We analyze a simple dynamical model of glasses, based on the idea that each particle is trapped in a local potential well, which itself evolves due to hopping of neighbouring particles. The glass transition is signalled by the fact that the equilibrium distribution ceases to be normalisable, and dynamics becomes non-st...
1995-06-07
2009-10-28
[ "cond-mat" ]
Jean-Philippe Bouchaud, Alain Comtet, C\'ecile Monthus
cond-mat/9506032
Haldane's Fractional Statistics and the Lowest Landau Level on a Torus
The Lowest Landau Level on a torus is studied. The dimension of the many-body Hilbert space is obtained and is found to be different from the formula given by Haldane. Our result can be tested in numerical investigations of the low-energy spectrum of fractional quantum Hall states on a torus.
1995-06-07
2009-10-28
[ "cond-mat", "hep-th" ]
Ansar Fayyazuddin and Dingping Li
cond-mat/9506031
TDAE-\c60: Can a Mott insulator be a ferromagnet?
Motivated by the structure of TDAE-\c60, we derive a multicomponent superexchange Hamiltonian for the spins and orbital (``isospin'') degrees of freedom in the Mott-insulating phase. We explore its phase diagram and identify points of special interest: an SU(4) antiferromagnet (solved by Sutherland) and two ferromagnet...
1995-06-07
2007-05-23
[ "cond-mat" ]
Daniel P. Arovas and Assa Auerbach
cond-mat/9506029
UNREALIZABLE LEARNING IN FEEDFORWARD NEURAL NETWORKS
Statistical mechanics is used to study unrealizable generalization in two large feed-forward neural networks with binary weights and output, a perceptron and a tree committee machine. The student is trained by a teacher being larger, i.e. having more units than the student. It is shown that this is the same as using tr...
1995-06-07
2007-05-23
[ "cond-mat" ]
Matts Sporre
cond-mat/9506033
Critical Josephson Current in a Model Pb/YBa_2Cu_3O_7 Junction
In this article we consider a simple model for a c--axis Pb/YBa_2Cu_3O_{7-\delta} Josephson junction. The observation of a nonzero current in such a junction by Sun et al. [A. G. Sun, D. A. Gajewski, M. B. Maple, R. C. Dynes, Phys. Rev. Lett. 72, 2267 (1994)] has been taken as evidence against d--wave superconductivity...
1995-06-07
2009-10-28
[ "cond-mat" ]
W. A. Atkinson and J. P. Carbotte
cond-mat/9506030
Chaos in resonant-tunneling superlattices
Spatio-temporal chaos is predicted to occur in n-doped semiconductor superlattices with sequential resonant tunneling as their main charge transport mechanism. Under dc voltage bias, undamped time-dependent oscillations of the current (due to the motion and recycling of electric field domain walls) have been observed i...
1995-06-07
2009-10-28
[ "cond-mat", "chao-dyn", "nlin.CD" ]
O.M. Bulashenko and L.L. Bonilla (Univ. Carlos III de Madrid)
cond-mat/9506028
Equilibrium Ensemble Approach to Disordered Systems I: General Theory, Exact Results
An outline of Morita's equilibrium ensemble approach to disordered systems is given, and hitherto unnoticed relations to other, more conventional approaches in the theory of disordered systems are pointed out. It is demonstrated to constitute a generalization of the idea of grand ensembles and to be intimately related ...
1995-06-07
2009-10-28
[ "cond-mat" ]
Reimer K\"uhn
cond-mat/9506025
Lattice-Gas Models of Adsorption in the Double Layer
The theory of statistical-mechanical lattice-gas modeling of adsorption is reviewed and shown to be applicable to a range of electrochemical problems dominated by effective, lateral adsorbate--adsorbate interactions. A general strategy for applying the method to specific systems is outlined, which includes microscopic ...
1995-06-06
2007-05-23
[ "cond-mat", "chem-ph", "mtrl-th" ]
P.A. Rikvold, J. Zhang, Y.-E. Sung, and A. Wieckowski
cond-mat/9506022
Quantitative Description of $V_2O_3$ by the Hubbard Model in Infinite Dimensions
We show that the analytic single-particle density of states and the optical conductivity for the half-filled Hubbard model on the Bethe lattice in infinite dimensions describe quantitatively the behavior of the gap and the kinetic energy ratio of the correlated insulator $V_2O_3$. The form of the optical conductivity s...
1995-06-06
2013-07-22
[ "cond-mat" ]
Jongbae Hong and Hae-Young Kee
cond-mat/9506023
DIFFUSIVE TRANSPORT IN A ONE DIMENSIONAL DISORDERED POTENTIAL INVOLVING CORRELATIONS
This article deals with transport properties of one dimensional Brownian diffusion under the influence of a correlated quenched random force, distributed as a two-level Poisson process. We find in particular that large time scaling laws of the position of the Brownian particle are analogous to the uncorrelated case. We...
1995-06-06
2009-10-28
[ "cond-mat" ]
Cecile MONTHUS
cond-mat/9506026
Semiclassical description of spin ladders
The Heisenberg spin ladder is studied in the semiclassical limit, via a mapping to the nonlinear $\sigma$ model. Different treatments are needed if the inter-chain coupling $K$ is small, intermediate or large. For intermediate coupling a single nonlinear $\sigma$ model is used for the ladder. Its predicts a spin gap fo...
1995-06-06
2009-10-28
[ "cond-mat" ]
D. Senechal
cond-mat/9506024
DIFFUSION IN ONE DIMENSIONAL RANDOM MEDIUM AND HYPERBOLIC BROWNIAN MOTION
Classical diffusion in a random medium involves an exponential functional of Brownian motion. This functional also appears in the study of Brownian diffusion on a Riemann surface of constant negative curvature. We analyse in detail this relationship and study various distributions using stochastic calculus and function...
1995-06-06
2016-08-31
[ "cond-mat" ]
Alain COMTET, Cecile MONTHUS
cond-mat/9506018
Hartree-Fock ground state of the composite fermion metal
Within the Hartree-Fock approximation the ground state of the composite fermion metal is found. We observe that the single-particle energy spectrum is dominated by the logarithmic interaction exchange term which leads to an infinite jump of the single-particle energy at the Fermi momentum. It is shown that the Hartree-...
1995-06-05
2015-06-25
[ "cond-mat" ]
P.Sitko and L.Jacak
cond-mat/9506017
Scaling, Propagation, and Kinetic Roughening of Flame Fronts in Random Media
We introduce a model of two coupled reaction-diffusion equations to describe the dynamics and propagation of flame fronts in random media. The model incorporates heat diffusion, its dissipation, and its production through coupling to the background reactant density. We first show analytically and numerically that there...
1995-06-05
2016-08-15
[ "cond-mat", "adap-org", "nlin.AO" ]
N. Provatas, T. Ala-Nissila, M. Grant, K. R. Elder, and L. Pich\'e
cond-mat/9506020
Energy Barriers for Flux Lines in 3 Dimensions
I determine the scaling behavior of the free energy barriers encountered by a flux line in moving through a three-dimensional random potential. A combination of numerical simulations and analytic arguments suggest that these barriers scale with the length of the line in the same way as the fluctuation in the free energ...
1995-06-05
2009-10-28
[ "cond-mat" ]
Barbara Drossel
cond-mat/9506019
Theory of the Spin Gap in High Temperature Superconductors
We analyze pairing in two dimensional spin liquids. We argue that interplane pairing enhanced by magnetic correlations is the most plausible explanation of the spin gap phenomenon observed in underdoped cuprates. The details of the pairing theory depend on the in-plane antiferromagnetic correlations. We consider two mo...
1995-06-05
2009-10-28
[ "cond-mat" ]
B. L. Altshuler, L. B. Ioffe, A. J. Millis
cond-mat/9506021
Self-Organized Criticality and Synchronization in the Forest-Fire Model
Depending on the rule for tree growth, the forest-fire model shows either self-organized criticality with rule-dependent exponents, or synchronization, or an intermediate behavior. This is shown analytically for the one-dimensional system, but holds evidently also in higher dimensions.
1995-06-05
2009-10-28
[ "cond-mat" ]
Barbara Drossel (MIT)
cond-mat/9506016
FRACTURING OF BRITTLE HOMOGENEOUS SOLIDS. FINITE SIZE SCALINGS
Using a two dimensional lattice model we investigate the crack growth under the influence of remote tensile forces as well as due to an internally applied pressure (hydraulic fracturing). For homogeneous elastic properties we present numerical finite-size scalings for the breaking stresses and pressures in terms of cra...
1995-06-03
2008-12-18
[ "cond-mat" ]
Frank Tzschichholz (PMMH URA 857, ESPCI, Paris, France)
cond-mat/9506014
Fracton Superconductivity in Quasicrystals --- A Theoretical Possibility Suggested by Experiment
Scattering of electrons due to fractons can result in a resistivity that {\it decreases} with temperature. Such a behavior also appears in real quasicrystals. If this is then attributed to fracton scattering, fracton-superconductivity would be theoretically possible. By fitting with the scattering result the experiment...
1995-06-02
2008-02-03
[ "cond-mat" ]
K. Moulopoulos and F. Cyrot-Lackmann
cond-mat/9506010
MICROWAVE-INDUCED RESONANT REFLECTION AND LOCALIZATION OF BALLISTIC ELECTRONS IN QUANTUM MICROCHANNELS
We show that electron transport in a ballistic microchannel supporting both propagating and reflected modes can be completely blocked by applying a microwave electromagnetic field. The effect is due to resonant reflection caused by multiple coherent electron-photon scattering involving at least two spatially localized ...
1995-06-02
2009-10-28
[ "cond-mat" ]
L. Y. Gorelik, M. Jonson, and R. I. Shekhter
cond-mat/9506009
Correlation effects in ionic crystals: I. The cohesive energy of MgO
High-level quantum-chemical calculations, using the coupled-cluster approach and extended one-particle basis sets, have been performed for (Mg2+)n (O2-)m clusters embedded in a Madelung potential. The results of these calculations are used for setting up an incremental expansion for the correlation energy of bulk MgO. ...
1995-06-02
2009-10-28
[ "cond-mat" ]
Klaus Doll, Michael Dolg, Peter Fulde, Hermann Stoll
cond-mat/9506011
Exact Results on Superconductivity due to Interband Coupling
We present a family of exactly solvable models at arbitrary filling in any dimensions which exhibit novel superconductivity with interband pairing. By the use of the hidden $SU(2)$ algebra the Hamiltonians were diagonalized explicitly. The zero-temperature phase diagrams and the thermodynamic properties are discussed. ...
1995-06-02
2009-10-28
[ "cond-mat" ]
Y. Morita, Y. Hatsugai and M. Kohmoto
cond-mat/9506013
Spin Waves in Quantum Antiferromagnets
Using a self-consistent mean-field theory for the $S=1/2$ Heisenberg antiferromagnet Kr\"uger and Schuck recently derived an analytic expression for the dispersion. It is exact in one dimension ($d=1$) and agrees well with numerical results in $d=2$. With an expansion in powers of the inverse coordination number $1/Z$ ...
1995-06-02
2009-10-28
[ "cond-mat" ]
B. Kleine, G.S. Uhrig and E. M\"uller-Hartmann
cond-mat/9506012
Transmission Resonance in an Infinite Strip of Phason-Defects of a Penrose Approximant Network
An exact method that analytically provides transfer matrices in finite networks of quasicrystalline approximants of any dimensionality is discussed. We use these matrices in two ways: a) to exactly determine the band structure of an infinite approximant network in analytical form; b) to determine, also analytically, th...
1995-06-02
2016-08-31
[ "cond-mat" ]
K. Moulopoulos and S. Roche
cond-mat/9506008
UNREALIZABLE LEARNING IN BINARY FEEDFORWARD NEURAL NETWORKS
Statistical mechanics is used to study unrealizable generalization in two large feed-forward neural networks with binary weights and output, a perceptron and a tree committee machine. The student is trained by a teacher being larger, i.e. having more units than the student. It is shown that this is the same as using tr...
1995-06-02
2007-05-23
[ "cond-mat" ]
Matts Sporre (Nordita)
cond-mat/9505157
Quantum saturation and condensation of excitons in Cu$_2$O: a theoretical study
Recent experiments on high density excitons in Cu$_2$O provide evidence for degenerate quantum statistics and Bose-Einstein condensation of this nearly ideal gas. We model the time dependence of this bosonic system including exciton decay mechanisms, energy exchange with phonons, and interconversion between ortho (trip...
1995-06-01
2009-10-28
[ "cond-mat" ]
G.M. Kavoulakis, Gordon Baym and J.P. Wolfe
cond-mat/9506003
Nonlinear optical response from excitons in soliton lattice systems of doped conjugated polymers
Exciton effects on conjugated polymers are investigated in soliton lattice states. We use the Su-Schrieffer-Heeger 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. The th...
1995-06-01
2007-05-23
[ "cond-mat", "chem-ph", "mtrl-th" ]
Kikuo Harigaya
cond-mat/9505158
Adiabatic Effective Action for Vortices in Neutral and Charged Superfluids
Adiabatic effective action for vortices in neutral and charged superfluids at zero temperature are calculated using the topological Landau-Ginzburg theory recently proposed by Hatsuda, Yahikozawa, Ao and Thouless, and vortex dynamics are examined. The Berry phase term arising in the effective action naturally yields th...
1995-06-01
2016-08-31
[ "cond-mat", "hep-th", "supr-con" ]
M. Hatsuda, M. Sato, S. Yahikozawa and T. Hatsuda
cond-mat/9506007
Finite Size Effects for the Dilute Coupling Derrida Model
We consider paramagnetic, spin-glass and ferromagnetic phases. At $T=0$ model gives for the some values of connectivity (near the critical) extremal suppression of finite size effects (decoding error probability).
1995-06-01
2016-08-31
[ "cond-mat" ]
A.E. Allakhverdyan and D.B. Saakian
cond-mat/9506002
On the universality of a class of annihilation-coagulation models
A class of $d$-dimensional reaction-diffusion models interpolating continuously between the diffusion-coagulation and the diffusion-annihilation models is introduced. Exact relations among the observables of different models are established. For the one-dimensional case, it is shown how correlations in the initial stat...
1995-06-01
2009-10-28
[ "cond-mat" ]
Daniele Balboni, Pierre-Antoine Rey and Michel Droz
cond-mat/9506005
On surface properties of two-dimensional percolation clusters
The two-dimensional site percolation problem is studied by transfer-matrix methods on finite-width strips with free boundary conditions. The relationship between correlation-length amplitudes and critical indices, predicted by conformal invariance, allows a very precise determination of the surface decay-of-correlation...
1995-06-01
2009-10-28
[ "cond-mat" ]
S L A de Queiroz
cond-mat/9506006
Experimental Evidence for a Coulomb Gap in Two Dimensions
We have studied the resistivity, $\rho$, of a two-dimensional electron system in silicon in the temperature range 200 mK < T < 7.5 K at zero magnetic field at low electron densities, when the electron system is in the insulating regime. Our results show that at an intermediate temperature range $\rho=\rho_0 exp[(T_0/T)...
1995-06-01
2009-10-28
[ "cond-mat" ]
Whitney Mason, S. V. Kravchenko, G. E. Bowker, and J. E. Furneaux
cond-mat/9506004
Role of phason-defects on the conductance of a 1-d quasicrystal
We have studied the influence of a particular kind of phason-defect on the Landauer resistance of a Fibonacci chain. Depending on parameters, we sometimes find the resistance to decrease upon introduction of defect or temperature, a behavior that also appears in real quasicrystalline materials. We demonstrate essential...
1995-06-01
2009-10-28
[ "cond-mat" ]
K. Moulopoulos and S. Roche
cond-mat/9506001
Classical and Quantum Dynamics of a Periodically Driven Particle in a Triangular Well
We investigate the correspondence between classical and quantum mechanics for periodically time dependent Hamiltonian systems, using the example of a periodically forced particle in a one-dimensional triangular well potential. In particular, we consider quantum mechanical Floquet states associated with resonances in th...
1995-06-01
2017-11-01
[ "cond-mat" ]
Michael E. Flatt\'e and Martin Holthaus
cond-mat/9506015
Topological effects on magnitude of persistent current in a ring
We show that defects in 1D rings decrease the conductance (when the ring is opened up) many more times than it decreases the persistent currents. This means that the states in such a 1D ring are very sensitive to twisting of boundary condition but conductance of the system is small. In 1D the electron effectively sees ...
1995-05-31
2007-05-23
[ "cond-mat" ]
P. Singha Deo
cond-mat/9505154
Skyrme Crystal In A Two-Dimensional Electron Gas
The ground state of a two-dimensional electron gas at Landau level filling factors near $\nu =1$ is a Skyrme crystal with long range order in the positions and orientations of the topologically and electrically charged elementary excitations of the $\nu=1$ ferromagnetic ground state. The lowest energy Skyrme crystal is...
1995-05-31
2009-10-28
[ "cond-mat" ]
L.Brey, H.A.Fertig, R.Cote and A.H.MacDonald
cond-mat/9505153
Perturbation of Tunneling Processes by Mechanical Degrees of Freedom in Mesoscopic Junctions
We investigate the perturbation in the tunneling current caused by non-adiabatic mechanical motion in a mesoscopic tunnel junction. A theory introduced by Caroli et al. \cite{bi1,bi2,bi3} is used to evaluate second order self-energy corrections for this non-equilibrium situation lacking translational invariance. Inelas...
1995-05-31
2009-10-28
[ "cond-mat" ]
N. F. Schwabe (Department of Theoretical Physics, University of Oxford), A. N. Cleland, M. C. Cross, M. L. Roukes (California Institute of Technology)
cond-mat/9505152
Composite fermions traversing a potential barrier
Using a composite fermion picture, we study the lateral transport between two two-dimensional electron gases, at filling factor 1/2, separated by a potential barrier. In the mean field approximation, composite fermions far from the barrier do not feel a magnetic field while in the barrier region the effective magnetic ...
1995-05-31
2009-10-28
[ "cond-mat" ]
L.Brey and C.Tejedor
cond-mat/9505155
Hot and repulsive traffic flow
We study a message passing model, applicable also to traffic problems. The model is implemented in a discrete lattice, where particles move towards their destination, with fluctuations around the minimal distance path. A repulsive interaction between particles is introduced in order to avoid the appearance of traffic j...
1995-05-31
2009-10-28
[ "cond-mat" ]
I. Campos, A. Tarancon (Univ. Zaragoza, Spain), F. Clerot (France Telecom, CNET, Lannion, France), and L.A. Fernandez (Univ. Complutense de Madrid, Spain)