1. State Key Laboratory of Magnetism, Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
2. Clarendon Laboratory, Department of Physics, University of Oxford, Oxford OX1 3PU, United Kingdom
3. Department of Materials Engineering and the Ilse Katz Institute for Nanoscale Science and Technology, Ben-Gurion University of the Negev, Beer-Sheva 84105, Israel
4. Department of Physics and Quantum Theory Project, University of Florida, Gainesville, Florida 32611, USA
5. Center for Nanophase Materials Sciences and Computer Science and Mathematics Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831-6493, USA