1. Physical Science and Engineering Division King Abdullah University of Science and Technology Thuwal 23955‐6900 Saudi Arabia
2. Tianjin Key Laboratory of Low Dimensional Materials Physics and Processing Technology Institute of Advanced Materials Physics School of Science Tianjin University Tianjin 300350 China
3. Department of Physics University of California at Berkeley Berkeley CA 94720 USA
4. Physics Department Georgetown University Washington DC 20057 USA
5. Aix‐Marseille Université CNRS CINaM Marseille France