14,115 research outputs found
Anomalous Hall effect in heavy electron materials
We propose a new empirical formula for the anomalous Hall effect in heavy
electron materials based on a phenomenological two-fluid description of the
f-electron states. The new formula incorporates two previous theories proposed
by Fert and Levy in 1987 and Kontani et al. in the early 1990s and takes into
account both incoherent and coherent skew scatterings from local and itinerant
f-electrons. We perform experimental analysis in several heavy electron
compounds and show that the new formula provides a consistent description of
the evolution of the Hall coefficient in the whole temperature range down to
only a few Kelvin.Comment: 6 pages, 4 figure
APPLE: Approximate Path for Penalized Likelihood Estimators
In high-dimensional data analysis, penalized likelihood estimators are shown
to provide superior results in both variable selection and parameter
estimation. A new algorithm, APPLE, is proposed for calculating the Approximate
Path for Penalized Likelihood Estimators. Both the convex penalty (such as
LASSO) and the nonconvex penalty (such as SCAD and MCP) cases are considered.
The APPLE efficiently computes the solution path for the penalized likelihood
estimator using a hybrid of the modified predictor-corrector method and the
coordinate-descent algorithm. APPLE is compared with several well-known
packages via simulation and analysis of two gene expression data sets.Comment: 24 pages, 9 figure
Universal Behavior in Heavy Electron Materials
We present our finding that an especially simple scaling expression describes
the formation of a new state of quantum matter, the Kondo Fermi liquid (KL) in
heavy electron materials. Emerging at as a result of the collective
coherent hybridization of localized f electrons and conduction electrons, the
KL possesses a non-Landau density of states varying as
. We show that four independent experimental
probes verify this scaling behavior and that for CeIrIn the KL state
density is in excellent agreement with the recent microscopic calculations of
hybridization in this material by Shim, Haule, and Kotliar.Comment: 4 pages, 5 figure
Nonequilibrium transport through a quantum dot weakly coupled to Luttinger liquids
We study the nonequlibrium transport through a quantum dot weakly coupled to
Luttinger liquids (LL). A general current expression is derived by using
nonequilibrium Green function method. Then a special case of the dot with only
a single energy level is discussed. As a function of the dot's energy level, we
find that the current as well as differential conductance is strongly
renormalized by the interaction in the LL leads. In comparison with the system
with Fermi liquid (FL) leads, the current is suppressed, consistent with the
suppression of the electron tunneling density of states of the LL; and the
outset of the resonant tunneling is shifted to higher bias voltages. Besides,
the linear conductance obtained by Furusaki using master equation can be
reproduced from our result.Comment: 8 pages, 3 figures, Late
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