1. Department of Materials and Environmental Chemistry, Stockholm University, S-10691 Stockholm, Sweden
2. Department of Physics, Augsburg University, D-86135 Augsburg, Germany
3. Extreme Conditions Physics Research Laboratory, Physics of Energy Materials Research Unit, Department of Physics, Faculty of Science, Chulalongkorn University, Bangkok 10330, Thailand
4. Thailand Center of Excellence in Physics, Commission on Higher Education, 328 Si Ayutthaya Road, Bangkok 10400, Thailand
5. Theoretical Physics Division, Department of Physics, Chemistry and Biology (IFM), Linköping University, SE-581 83 Linköping, Sweden
6. Department of Mechanical Engineering and Tsinghua-Foxconn Nanotechnology Research Center, Tsinghua University, Beijing 10084, China
7. Department of Physics, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, United States