1. State Key Laboratory for Chemo/Biosensing and Chemometrics, and Key Laboratory for Micro-Nano Optoelectronic Devices of Ministry of Education, Hunan University, Changsha 410082, China, Institute of Physics, Chinese Academy of Sciences, P.O. Box 603, Beijing 100080, China, and National Amorphous and Nanocrystalline Alloy Engineering Research Center, Central Iron and Steel Research Institute, XueYuan Nan Road No. 76, Beijing 100081, China