中国物理B ›› 2013, Vol. 22 ›› Issue (2): 27307-027307.doi: 10.1088/1674-1056/22/2/027307

• CONDENSED MATTER: ELECTRONIC STRUCTURE, ELECTRICAL, MAGNETIC, AND OPTICAL PROPERTIES • 上一篇    下一篇

Transport through artificial single-molecule magnets: Spin-pair state sequential tunneling and Kondo effects

牛鹏斌, 王强, 聂一行   

  1. Institute of Theoretical Physics and Department of Physics, Shanxi University, Taiyuan 030006, China
  • 收稿日期:2012-05-30 修回日期:2012-08-31 出版日期:2013-01-01 发布日期:2013-01-01
  • 基金资助:
    Project supported by the National Natural Science Foundation of China (Grant Nos. 10974124 and 11004124) and Shanxi Provincial Natural Science Foundation of China (Grant No. 2009011001-1).

Transport through artificial single-molecule magnets: Spin-pair state sequential tunneling and Kondo effects

Niu Peng-Bin (牛鹏斌), Wang Qiang (王强), Nie Yi-Hang (聂一行)   

  1. Institute of Theoretical Physics and Department of Physics, Shanxi University, Taiyuan 030006, China
  • Received:2012-05-30 Revised:2012-08-31 Online:2013-01-01 Published:2013-01-01
  • Contact: Nie Yi-Hang E-mail:nieyh@sxu.edu.cn
  • Supported by:
    Project supported by the National Natural Science Foundation of China (Grant Nos. 10974124 and 11004124) and Shanxi Provincial Natural Science Foundation of China (Grant No. 2009011001-1).

摘要: The transport properties of an artificial single-molecule magnet based on a CdTe quantum dot doped with a single Mn+2 ion (S=5/2) are investigated by the non-equilibrium Green function method. We consider a minimal model where the Mn-hole exchange coupling is strongly anisotropic so that spin-flip is suppressed and the impurity spin S and a hole spin s entering quantum dot are coupled into spin pair states with (2S+1) sublevels. In the sequential tunneling regime, the differential conductance exhibits (2S+1) possible peaks, corresponding to resonance tunneling via (2S+1) sublevels. At low temperature, Kondo physics dominates transport and (2S+1) Kondo peaks occur in the local density of states and conductance. These peaks originate from the spin-singlet state formed by the holes in the leads and on the dot via higher-order processes and are related to the parallel and antiparallel spin pair states.

关键词: artificial single-molecule magnet, Hubbard Green function, spin-pair Kondo effect

Abstract: The transport properties of an artificial single-molecule magnet based on a CdTe quantum dot doped with a single Mn+2 ion (S=5/2) are investigated by the non-equilibrium Green function method. We consider a minimal model where the Mn-hole exchange coupling is strongly anisotropic so that spin-flip is suppressed and the impurity spin S and a hole spin s entering quantum dot are coupled into spin pair states with (2S+1) sublevels. In the sequential tunneling regime, the differential conductance exhibits (2S+1) possible peaks, corresponding to resonance tunneling via (2S+1) sublevels. At low temperature, Kondo physics dominates transport and (2S+1) Kondo peaks occur in the local density of states and conductance. These peaks originate from the spin-singlet state formed by the holes in the leads and on the dot via higher-order processes and are related to the parallel and antiparallel spin pair states.

Key words: artificial single-molecule magnet, Hubbard Green function, spin-pair Kondo effect

中图分类号:  (Quantum dots)

  • 73.63.Kv
72.10.-d (Theory of electronic transport; scattering mechanisms) 72.15.Qm (Scattering mechanisms and Kondo effect) 73.63.-b (Electronic transport in nanoscale materials and structures)