Origin of Ferromagnetism in Zn_(1−x)Co_(x)O Thin Films:Evidences Provided by Hard and Soft X-Ray Absorption Spectroscopy  

作　　者：XI Shi-Bo CUI Ming-Qi QIN Xiu-Fang XU Xiao-Hong XU Wei ZHENG Lei ZHOU Jing LIU Li-Juan YANG Dong-Liang GUO Zhi-Ying 席识博;崔明启;秦秀芳;许小红;徐伟;郑雷;周靖;刘利娟;杨栋亮;郭志英(Institute of High Energy Physics,Chinese Academy of Sciences,Beijing 100049;School of Chemistry and Materials Science,Shanxi Normal University,Linfen 041004)

机构地区：[1]Institute of High Energy Physics,Chinese Academy of Sciences,Beijing 100049 [2]School of Chemistry and Materials Science,Shanxi Normal University,Linfen 041004

出　　处：《Chinese Physics Letters》2012年第12期223-227,共5页中国物理快报（英文版）

基　　金：Supported by the National Natural Science Foundation of China under Grant No 11075176;the Graduate Student Inno-vation Fund of NSRL(20090618S).

摘　　要：Although dilute magnetic semiconductors have promising potentials in spintronics applications,the mechanism of their ferromagnetism remains ambiguous.The extensive theoretical models and exotic experimental evidences provide self-consistent but usually contradictory explanations on its either intrinsic or extrinsic origins.We find room temperature ferromagnetism in a series of Zn_(1-x)Co_(x)O(0.03≤x≤0.10)thin films prepared using magnetron co-sputtering method and treated with post-annealing at temperatures 350℃ and 500℃.The origin of the ferromagnetism is investigated in terms of electronic structure combining hard x-ray absorption spectroscopy(XAS)at Zn and Co K-edge,and soft x-ray XAS at O K-edge and Co L_(2,3)-edge.The full multiple scattering theory is employed to reinforce the interpretation of the XAS spectra,which concludes that full substitution of zinc by cobalt is responsible for the room temperature ferromagnetism due to the d states of cobalt within the framework of bound magnetic polaron.Moreover,the evidence of cobalt nanoclusters is detected at highly doped and annealed samples.The first principles calculation confirms the electronic structural evidences via the formation energy.

关 键 词：COBALT DILUTE SUBSTITUTION 

分 类 号：O64[理学—物理化学]