1. Department of Physics, Harbin Institute of Technology, 150001 Harbin, China
2. Shenzhen Key Laboratory of Thermoelectric Materials, Department of Physics, Southern University of Science and Technology, 518055 Shenzhen, China
3. School of Materials Science and Engineering, Shaanxi Normal University, 710119 Xi’an, China
4. Faculty of Materials Science and Engineering, Kunming University of Science and Technology, 650093 Kunming, China