Numerical study of Kondo impurity models with strong potential scattering: Reverse Kondo effect and antiresonance

Physical review. B, Condensed matter (Impact Factor: 3.66). 06/2011; 84(17). DOI: 10.1103/PhysRevB.84.174402
Source: arXiv


Accurate numerical results are derived for transport properties of Kondo
impurity systems with potential scattering and orbital degeneracy. Using the
continuous-time quantum Monte Carlo (CT-QMC) method, static and dynamic
physical quantities are derived in a wide temperature range across the Kondo
temperature T_K. With strong potential scattering, the resistivity tends to
decrease with decreasing temperature, in contrast to the ordinary Kondo effect.
Correspondingly, the quasi-particle density of states obtains the antiresonance
around the Fermi level. Thermopower also shows characteristic deviation from
the standard Kondo behavior, while magnetic susceptibility follows the
universal temperature dependence even with strong potential scattering. It is
found that the t-matrix in the presence of potential scattering is not a
relevant quantity for the Friedel sum rule, for which a proper limit of the
f-electron Green's function is introduced. The optical theorem is also
discussed in the context of Kondo impurity models with potential scattering. It
is shown that optical theorem holds not only in the Fermi-liquid range but also
for large energies, and therefore is less restrictive than the Friedel sum

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Available from: Shintaro Hoshino, Oct 06, 2015
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    ABSTRACT: In recent years inelastic spin-flip spectroscopy using a lowtemperature scanning tunneling microscope has been a very successful tool for studying not only individual spins but also complex coupled systems. When these systems interact with the electrons of the supporting substrate correlated manyparticle states can emerge, making them ideal prototypical quantum systems. The spin systems, which can be constructed by arranging individual atoms on appropriate surfaces or embedded in synthesized molecular structures, can reveal very rich spectral features. Up to now the spectral complexity has only been partly described. This manuscript shows that perturbation theory enables one to describe the tunneling transport, reproducing the differential conductance with surprisingly high accuracy. Well established scattering models, which include Kondo-like spin-spin and potential interactions, are expanded to enable calculation of arbitrary complex spin systems in reasonable time scale and the extraction of important physical properties. The emergence of correlations between spins and, in particular, between the localized spins and the supporting bath electrons are discussed and related to experimentally tunable parameters. These results might stimulate new experiments by providing experimentalists with an easily applicable modeling tool.
    New Journal of Physics 06/2015; 17:063016. DOI:10.1088/1367-2630/17/6/063016 · 3.56 Impact Factor