1. College of Physics, Chongqing University, Chongqing 401331, China
2. NUS (Chongqing) Research Institute, Chongqing 401123, China
3. School of Chemistry and Materials Science of Shanxi Normal University & Key Laboratory of Magnetic Molecules and Magnetic Information Materials of Ministry of Education, Taiyuan 03000, China
4. Department of Materials Science and Engineering, National University of Singapore, Singapore 117575, Singapore