1. Electronic Materials Research Laboratory, Key Laboratory of the Ministry of Education and International Center for Dielectric Research, School of Electronic Science and Engineering, Xi’an Jiaotong University, Xi’an 710049, China
2. Department of Physics, University of Oxford, Parks Road, Oxford OX1 3PU, England
3. Department of Physics, University of Warwick, Gibbet Hill Road, Coventry CV4 7AL,
England
4. Department of Chemistry and 4D LABS, Simon Fraser University, 8888 University Drive, Burnaby, British Columbia V5A 1S6,
Canada