中国物理B ›› 2009, Vol. 18 ›› Issue (11): 5047-5054.doi: 10.1088/1674-1056/18/11/073

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A Green's function model for ferromagnetism and spin excitations of (Ga Mn)As diluted magnetic semiconductors

刘贵斌, 刘邦贵   

  1. Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China;Beijing National Laboratory for Condensed Matter Physics, Beijing 100190, China
  • 收稿日期:2009-05-04 修回日期:2009-05-31 出版日期:2009-11-20 发布日期:2009-11-20
  • 基金资助:
    Project supported by the National Nature Science Foundation of China (Grant Nos 10774180, 90406010 and 6062109), Funds of the Chinese Academy of Sciences for Key Topics in Innovation Engineering (Grant No KJCX2.YW.W09-5) and the National Basic Research Program of China (Grant No 2005CB623602).

A Green's function model for ferromagnetism and spin excitations of (Ga Mn)As diluted magnetic semiconductors

Liu Gui-Bin(刘贵斌) and Liu Bang-Gui(刘邦贵)†   

  1. Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China;Beijing National Laboratory for Condensed Matter Physics, Beijing 100190, China
  • Received:2009-05-04 Revised:2009-05-31 Online:2009-11-20 Published:2009-11-20
  • Supported by:
    Project supported by the National Nature Science Foundation of China (Grant Nos 10774180, 90406010 and 6062109), Funds of the Chinese Academy of Sciences for Key Topics in Innovation Engineering (Grant No KJCX2.YW.W09-5) and the National Basic Research Program of China (Grant No 2005CB623602).

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摘要： We study (Ga, Mn)As diluted magnetic semiconductors in terms of the Ruderman--Kittel--Kasuya--Yosida quantum spin model in Green's function approach. Random distributions of the magnetic atoms are treated by using an analytical average of magnetic configurations. Average magnetic moments and spin excitation spectra as functions of temperature can be obtained by solving self-consistent equations, and the Curie temperature TC is given explicitly. TC is proportional to magnetic atomic concentration, and there exists a maximum for TC as a function of carrier concentration. Applied to (Ga, Mn)As, the theoretical results are consistent with experiment and the experimental TC can be obtained with reasonable parameters. This modelling can also be applied to other diluted magnetic semiconductors.

Abstract: We study (Ga, Mn)As diluted magnetic semiconductors in terms of the Ruderman--Kittel--Kasuya--Yosida quantum spin model in Green's function approach. Random distributions of the magnetic atoms are treated by using an analytical average of magnetic configurations. Average magnetic moments and spin excitation spectra as functions of temperature can be obtained by solving self-consistent equations, and the Curie temperature TC is given explicitly. TC is proportional to magnetic atomic concentration, and there exists a maximum for TC as a function of carrier concentration. Applied to (Ga, Mn)As, the theoretical results are consistent with experiment and the experimental TC can be obtained with reasonable parameters. This modelling can also be applied to other diluted magnetic semiconductors.

Key words: diluted magnetic semiconductor, Green's function, Ruderman--Kittel--Kasuya--Yosida

中图分类号:  (Exchange and superexchange interactions)

  • 75.30.Et
75.50.Pp (Magnetic semiconductors) 75.50.Dd (Nonmetallic ferromagnetic materials) 75.30.Cr (Saturation moments and magnetic susceptibilities) 75.30.Kz (Magnetic phase boundaries (including classical and quantum magnetic transitions, metamagnetism, etc.)) 75.10.-b (General theory and models of magnetic ordering)