中国物理B ›› 2009, Vol. 18 ›› Issue (12): 5443-5450.doi: 10.1088/1674-1056/18/12/052

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Kondo effect in a deformed molecule coupled asymmetrically to ferromagnetic electrodes

蒋开明1, 王瑞强2   

  1. (1)Department of Physics, Shanghai Maritime University, Shanghai 201306, China; (2)Laboratory of Quantum Information Technology, Institute for Condensed Matter Physics, and School of Physics and Telecommunication Engineering, South China Normal University, Guangzhou 510006, China
  • 收稿日期:2009-07-21 修回日期:2009-07-21 出版日期:2009-12-20 发布日期:2009-12-20
  • 基金资助:
    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

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)   

  1. 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
  • Received:2009-07-21 Revised:2009-07-21 Online:2009-12-20 Published:2009-12-20
  • Supported by:
    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

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摘要： 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.

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.

Key words: Kondo effect, molecular spintronics, tunneling magnetoresistance, electron--phonon interaction, nonequilibrium Green function

中图分类号:  (Spin polarized transport)

  • 72.25.-b
72.15.Gd (Galvanomagnetic and other magnetotransport effects) 72.15.Qm (Scattering mechanisms and Kondo effect) 73.63.Kv (Quantum dots)