28 research outputs found
Anomalous Hall effect in a two dimensional electron gas with magnetic impurities
Magnetic impurities play an important role in many spintronics-related
materials. Motivated by this fact, we study the anomalous Hall effect in the
presence of magnetic impurities, focusing on two-dimensional electron systems
with Rashba spin-orbit coupling. We find a highly nonlinear dependence on the
impurity polarization, including possible sign changes. At small impurity
magnetizations, this is a consequence of the remarkable result that the linear
term is independent of the spin-orbit coupling strength. Near saturation of the
impurity spins, the anomalous Hall conductivity can be resonantly enhanced, due
to interference between potential and magnetic scattering.Comment: 5 pages, 3 figure
Universal diffusive decay of correlations in gapped one-dimensional systems
We apply a semiclassical approach to express finite temperature dynamical
correlation functions of gapped spin models analytically. We show that the
approach of [A. Rapp, G. Zarand, Phys. Rev. B 74, 014433 (2006)] can also be
used for the S=1 antiferromagnetic Heisenberg chain, whose lineshape can be
measured experimentally. We generalize our calculations to O(N) quantum spin
models and the sine-Gordon model in one dimension, and show that in all these
models, the finite temperature decay of certain correlation functions is
characterized by the same universal semiclassical relaxation function.Comment: 7 pages, 5 figures, final version appeared in Eur. Phys. J. B 67,
7-13 (2009
The Kondo Temperature of SU(4) Symmetric Quantum Dots
A path integral approach is used to derive a closed analytical expression for
the Kondo temperature of the SU(4) symmetrical Anderson model. In contrast to
the SU(2) case, the prefactor of the Kondo temperature is found to display a
peculiar orbital energy (gate voltage) dependence, reflecting the presence of
various SU(4) mixed valence fixed points. Our analytical expressions are tested
against and confirmed by numerical renormalization group computations.Comment: 4 pages, 5 figures and Suppl. Materia