1. CIMAP, UMR 6252 CNRS, ENSICAEN, UCBN, CEA, 6 Boulevard du Maréchal Juin, 14050 Caen Cedex, France
2. Key Laboratory of Materials Physics, Institute of Solid State Physics, Chinese Academy of Sciences, Hefei 230031, China
3. Max Planck Institute for Solid State Research, Heisenbergstrasse 1, 70569 Stuttgart, Germany
4. Department of Electrical and Computer Engineering, Virginia Commonwealth University, Richmond, Virginia 23284, United States