1,450 research outputs found
Electronic thermal conductivity of disordered metals
We calculate the thermal conductivity of interacting electrons in disordered
metals. In our analysis we point out that the interaction affects thermal
transport through two distinct mechanims, associated with quantum interference
corrections and energy exchange of the quasi particles with the electromagnetic
environment, respectively. The latter is seen to lead to a violation of the
Wiedemann-Franz law. Our theory predicts a strong enhancement of the Lorenz
ratio over the value which is predicted by the
Wiedemann-Franz law, when the electrons encounter a large environmental
impedance.Comment: 4 page
Free Magnetic Moments in Disordered Metals
The screening of magnetic moments in metals, the Kondo effect, is found to be
quenched with a finite probability in the presence of nonmagnetic disorder.
Numerical results for a disordered electron system show that the distribution
of Kondo temperatures deviates strongly from the result expected from random
matrix theory. A pronounced second peak emerges for small Kondo temperatures,
showing that the probability that magnetic moments remain unscreened at low
temperatures increases with disorder. Analytical calculations, taking into
account correlations between eigenfunction intensities yield a finite width for
the distribution in the thermodynamic limit. Experimental consequences for
disordered mesoscopic metals are discussed.Comment: RevTex 4.0, 4.3 pages, 4 EPS figures; typos fixed, reference added,
final published versio
Anomalous Hall effect in ferromagnetic disordered metals
The anomalous Hall effect in disordered band ferromagnets is considered in
the framework of quantum transport theory. A microscopic model of electrons in
a random potential of identical impurities including spin-orbit coupling is
used. The Hall conductivity is calculated from the Kubo formula for both, the
skew scattering and the side-jump mechanisms. The recently discussed Berry
phase induced Hall current is also evaluated within the model. The effect of
strong impurity scattering is analyzed and it is found to affect the ratio of
the non-diagonal (Hall) and diagonal components of the conductivity as well as
the relative importance of different mechanisms.Comment: Invited paper for Ann. Physik commemorating Paul Drud
Ward identities for disordered metals and superconductors
This article revisits Ward identities for disordered interacting normal
metals and superconductors. It offers a simple derivation based on gauge
invariance and recasts the identities in a new form that allows easy analysis
of the quasiparticle charge conservation (as e.g. in a normal metal) or
non-conservation (as e.g. in a d-wave superconductor).Comment: Discussion of decoherence at T=0 remove
Coherent transport in disordered metals out of equilibrium
We derive a formula for the quantum corrections to the electrical current for
a metal out of equilibrium. In the limit of linear current-voltage
characteristics our formula reproduces the well known Altshuler-Aronov
correction to the conductivity of a disordered metal. The current formula is
obtained by a direct diagrammatic approach, and is shown to agree with what is
obtained within the Keldysh formulation of the non-linear sigma model. As an
application we calculate the current of a mesoscopic wire. We find a
current-voltage characteristics that scales with , and calculate the
different scaling curves for a wire in the hot-electron regime and in the
regime of full non-equilibrium.Comment: 16 pages, 13 figure
Coherent transport in disordered metals: zero dimensional limit
We consider non-equilibrium transport in disordered conductors. We calculate
the interaction correction to the current for a short wire connected to
electron reservoirs by resistive interfaces. In the absence of charging effects
we find a universal current-voltage-characteristics. The relevance of our
calculation for existing experiments is discussed as well as the connection
with alternative theoretical approaches
Spectral statistics in disordered metals: a trajectories approach
We show that the perturbative expansion of the two-level correlation
function, , in disordered conductors can be understood
semiclassically in terms of self-intersecting particle trajectories. This
requires the extension of the standard diagonal approximation to include pairs
of paths which are non-identical but have almost identical action. The number
of diagrams thus produced is much smaller than in a standard field-theoretical
approach. We show that such a simplification occurs because has a
natural representation as the second derivative of free energy . We
calculate to 3-loop order, and verify a one-parameter scaling
hypothesis for it in 2d. We discuss the possibility of applying our ``weak
diagonal approximation'' to generic chaotic systems.Comment: 9 pages in REVTeX two-column format including 4 figures; submitted to
Phys.Rev.
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