Two magnetic regimes in doped ZnO corresponding to a dilute magnetic semiconductor and a dilute magnetic insulator

被引:333
作者
Behan, A. J. [1 ]
Mokhtari, A. [1 ]
Blythe, H. J. [1 ]
Score, D. [1 ]
Xu, X-H. [1 ]
Neal, J. R. [1 ]
Fox, A. M. [1 ]
Gehring, G. A. [1 ]
机构
[1] Univ Sheffield, Dept Phys & Astron, Sheffield S3 7RH, S Yorkshire, England
基金
英国工程与自然科学研究理事会;
关键词
D O I
10.1103/PhysRevLett.100.047206
中图分类号
O4 [物理学];
学科分类号
0702 ;
摘要
Films of ZnO doped with magnetic ions Mn and Co and, in some cases, with Al have been fabricated with a very wide range of carrier densities. Ferromagnetic behavior is observed in both insulating and metallic films, but not when the carrier density is intermediate. Insulating films exhibit variable range hopping at low temperatures and are ferromagnetic at room temperature due to the interaction of the localized spins with static localized states. The magnetism is quenched when carriers in the localized states become mobile. In the metallic (degenerate semiconductor) range, robust ferromagnetism reappears together with very strong magneto-optic signals and room temperature anomalous Hall data. This demonstrates the polarization of the conduction bands and indicates that, when ZnO is doped into the metallic regime, it behaves as a genuine magnetic semiconductor.
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页数:4
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