1. Electronic Materials Research Laboratory, Key Laboratory of the Ministry of Education & International Center for Dielectric Research, Xi’an Jiaotong University, Xi’an 710049, China
2. Department
of Chemistry and 4D LABORATORIES, Simon Fraser University, Burnaby, British Columbia V5A 1S6, Canada
3. Quantum
Condensed Matter Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States