13 research outputs found
Localization and Dephasing Driven by Magnetic Fluctuations in Low Carrier Density Colossal Magnetoresistance Materials
Localization and dephasing of conduction electrons in a low carrier density
ferromagnet due to scattering on magnetic fluctuations is considered. We claim
the existence of the "mobility edge", which separates the states with fast
diffusion and the states with slow diffusion; the latter is determined by the
dephasing time. When the "mobility edge" crosses the Fermi energy a large and
sharp change of conductivity is observed. The theory provides an explanation
for the observed temperature dependence of conductivity in ferromagnetic
semiconductors and manganite pyrochlores.Comment: 4 pages, 1 eps figure, LaTex2e, EPJ macro package (style files
included); final version, submitted to EPJ
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.Comment: 8 pages, latex, no figures. Submitted to Phys.Rev.
Statistics of fluctuations for two types of crossover: from ballistic to diffusive regime and from orthogonal to unitary ensemble
In our previous publication [Kogan et al, Phys. Rev. {\bf 48}, 9404 (1993)]
we considered the issue of statistics of radiation diffusively propagating in a
disordered medium. The consideration was in the framework of diagrammatic
techniques and a new representation for the intensity distribution function in
terms of connected diagrams only was proposed. Here we use similar approach to
treat the issue of statistics in the regime of the crossover between ballistic
and diffusive transport. We find that even small contribution from coherent
component decreases by one half the intensity distribution function for small
values of intensity and also produces oscillations of the distribution
function. We also apply this method to study statistics of fluctuations of wave
functions of chaotic electrons in a quantum dot in an arbitrary magnetic field,
by calculating the single state local density in the regime of the crossover
between the orthogonal and unitary ensemble.Comment: Revtex, 3 pages + 2 ps.figures in uuencoded file, a version which
clarifies and unites the results of two previous submission