arXiv subjects

E. Altshuler

Publications and source records attributed to E. Altshuler.

41 records · Page 3Linked to original sources

arXiv2000

On the importance of grain boundaries in high-Tc films: simulation results

The importance of the distribution and ``weakness'' of grain boundary junctions in the magnetic field dependence of the transport critical current in HTc films is assessed through simulations. The system is studied with the applied field either parallel or perpendicular to the c axis of the sample. For realistic sample parameters, it is demonstrated that the presence of ``high'' misorientation angles between grains depresses the zero - field critical current density in both orientations, and provokes a transition from pinning-mediated to Fraunhoffer-like field dependencies of the critical current density. Our results also suggest that there is a threshold misorientation angle above which the critical current density remains constant.

cond-mat.supr-con↗

arXiv1999

Universality of vortex avalanches in a type II superconductor with periodic pinning

In this work the robustness of a simple cellular automaton developed by Bassler and Paczuski to describe the critical state in type-II superconductors is studied. Two different configurations of pinning centers are introduced and a new universality class is found. The numerical values of the critical exponents were calculated following two scaling techniques to ensure the validity of our results.

cond-mat↗

arXiv1995

Quasiclassical approach to impurity effect on magnetooscillations in 2D metals

We develop a quasiclassical method based on the path integral formalism, to study the influence of disorder on magnetooscillations of the density of states and conductivity. The treatment is appropriate for electron systems in the presence of a random potential with large correlation length or a random magnetic field, which are characterisitic features of various 2D electronic systems presently studied in experiment. In particular, we study the system of composite fermions in the fractional quantum Hall effect device, which are coupled to the Chern--Simons field and subject to a long--range random potential.

cond-mat↗

arXiv1994

Theory of Shubnikov--De Haas Oscillations Around the $ν=1/2$ Filling Factor of the Landau Level: Effect of Gauge Field Fluctuations

We present a theory of magnetooscillations around the $ν=1/2$ Landau level filling factor based on a model with a fluctuating Chern--Simons field. The quasiclassical treatment of the problem is appropriate and leads to an unconventional $\exp\left[-(π/ω_cτ^*_{1/2})^4\right]$ behavior of the amplitude of oscillations. This result is in good qualitative agreement with available experimental data.

cond-mat↗

arXiv1994

Single Particle Relaxation in a Random Magnetic Field

We consider the single particle relaxation rate of 2D electrons subject to a random magnetic field. The density of states (DOS) oscillations in a uniform magnetic field (in addition to a random one) are studied. We define a gauge invariant single particle relaxation time as a parameter describing the amplitude of DOS oscillations. Unlike the conventional case of random potential scattering the broadening of the Landau levels does not depend on magnetic field.

cond-mat↗