1. College of Materials Science and Engineering, Sichuan University, 610064 Chengdu, China
2. Key Laboratory of Deep Underground Science and Engineering (Ministry of Education), College of Architecture and Environment, Sichuan University, Chengdu 610065, China
3. Sichuan Province Key Laboratory of Information Materials, Southwest Minzu University, 610041 Chengdu, China
4. Department of Physics, University of Texas at Arlington, Arlington, Texas 76019, United States