Kondo effect in a deformed molecule coupled asymmetrically to ferromagnetic electrodes
Wang Rui-Qiang(王瑞强)a)† and Jiang Kai-Ming(蒋开明)b)
a Laboratory of Quantum Information Technology, Institute for Condensed Matter Physics, and School of Physics and Telecommunication Engineering, South China Normal University, Guangzhou 510006, China; b Department of Physics, Shanghai Maritime University, Shanghai 201306, China
Abstract The nonequilibrium Kondo effect is studied in a molecule quantum dot coupled asymmetrically to two ferromagnetic electrodes by employing the nonequilibrium Green function technique. The current-induced deformation of the molecule is taken into account, modeled as interactions with a phonon system, and phonon-assisted Kondo satellites arise on both sides of the usual main Kondo peak. In the antiparallel electrode configuration, the Kondo satellites can be split only for the asymmetric dot-lead couplings, distinguished from the parallel configuration where splitting also exists, even though it is for symmetric case. We also analyze how to compensate the splitting and restore the suppressed zero-bias Kondo resonance. It is shown that one can change the TMR ratio significantly from a negative dip to a positive peak only by slightly modulating a local external magnetic field, whose value is greatly dependent on the electron--phonon coupling strength.
Received: 21 July 2009
Revised: 21 July 2009
Accepted manuscript online:
Fund: Project supported by the National
Natural Science Foundation of China (Grant No 10974058), the
Shanghai Natural Science Foundation of China (Grant No
09ZR1421400), Science and Technology Program of Shanghai Maritime
University (Grant No 2008475), and Post
Cite this article:
Wang Rui-Qiang(王瑞强) and Jiang Kai-Ming(蒋开明) Kondo effect in a deformed molecule coupled asymmetrically to ferromagnetic electrodes 2009 Chin. Phys. B 18 5443
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