Many-body Effects in Nanospintronics Devices

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概要

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• The physics of nanostructures have extended the frontier of quantum mechanics and have realized several important quantum effects, such as the Kondo effect in quantum dot (QD), the Aharonov-Bohm (AB) effect, etc. Recent fabrication technique of magnetic nanostructures evolved the active research field "spintronics". The nanospintronics devices possess basic interests since they provide a way to control the spin degrees of freedom and realize novel many-body states. We analyze the possibility of the Kondo effect in a QD coupled to two ferromagnetic leads. We show that for parallel alignment of magnetizations, the zero-bias anomaly is split. For antiparallel alignment and symmetric coupling, the Kondo resonance recovers and splitting is suppressed. We show that such anomalous behavior induces a negative large dip in the bias voltage dependence of the tunnel magnetoresistance. We also theoretically investigate the Ruderman-Kitte H Kasuya-Yosida (RKKY) interaction between two semiconducting QDs embedded in an AB ring. In such a system, the RKKY interaction can be controlled by the flux and the flux-dependent RKKY interaction dominates the conductance. For the ferromagnetic coupling, the amplitude of AB oscillations is enhanced by the Kondo correlations. For the antiferromagnetic coupling, the phase of AB oscillations is shifted by n. Discussed many-body effects, which were very recently demonstrated experimentally, can be utilized for future nanospintronics devices.

• 社団法人日本磁気学会の論文
• 2004-11-01

著者

• Utsumi Yasuhiro

  Max-planck-institut Fur Mikrostrukturphysik

• MAEKAWA Sadamichi

  Department of Applied Physics,Nagoya University

• Martinek Jan

  Institut fur Theoretische Festkoperphysik, Universitat Karlsruhe,

• Bruno Patrick

  Institute for Materials Research, Tohoku University

• Barnas Jozef

  Institute of Molecular Physics, Polish Academy of Sciences

• Martinek Jan

  Institut Fur Theoretische Festkoperphysik Universitat Karlsruhe

• Barnas Jozef

  Institute Of Molecular Physics Polish Academy Of Sciences

• Bruno Patrick

  Institute For Materials Research Tohoku University

• Maekawa Sadamichi

  Department Of Applied Physics Nagoya University

• Maekawa Sadamichi

  Department Of Physics Adam Mickiewicz University

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• Spin Correlations around Mobile Holes in an Antiferromagnet
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• Dynamics of Two Holes in the t-J Model
• Electronic State in Doped-Cuprates : IV-A Electronic States : IV Mechanisms of Superconductivity; Theory

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