Influence of Si doping on magnetic properties of (Ga,Mn)As

We have systematically investigated the magnetic properties of Si-doped (Ga,Mn)As films. When the Si content is low, both Curie temperature (T-C) and carrier density (p) decrease compared with undoped (Ga,Mn)As, whereas a monotonic increase of T-C and p is observed with further increase in the doping content of Si. We discuss the possible mechanism for the changes obtained by different Si doping contents and attribute the results to a competition between the existence of Si-Ga (Si substitutes for Ga site) that acts as a donor and Si-I (Si interstitials) which is in favor of the improvement of ferromagnetism. (C) 2008 Elsevier B.V. All rights reserved.

National Natural Science Foundation of China 10674130 1071031560521001Major State Basic Research of China 2007CB924903 Chinese Academy of Sciences KJCX2.YW.W09-1 The authors acknowledge J.F. Bi, Y.H. Zheng, H.J. Meng, RE Xu, and S. Yan for their help on sample preparation, and Y. Zhang and H.Y. Zhang for SQUID measurements. The authors also thank H.Z. Zheng, W. Guan and Y.T. Wang for valuable discussions. This work was supported partly by the National Natural Science Foundation of China under Grant nos. 10674130, 10710315 and 60521001, and the special funds for the Major State Basic Research Contract no. 2007CB924903 of China, and the Knowledge Innovation Program Project of Chinese Academy of Sciences No. KJCX2.YW.W09-1.