Institute of Mechanical Engineering, Nanjing University of Science and Technology, Nanjing 210094;
National Laboratory of Solid State Microstructures and Department of Physics, Nanjing University, Nanjing 210093;
National Laboratory of Solid State Microstructures and Department of Physics, Nanjing University, Nanjing 210093;
National Laboratory of Solid State Microstructures and Department of Physics, Nanjing University, Nanjing 210093;
Universit(a)t Leipzig, Fakult(a)t für Physik und Geowissenschaften, Institut für Experimentelle Physik Ⅱ, Linnéstrasse 5,D-04103 Leipzig, Germany;
Laboratorium voor Vaste-Stoffysica en Magnetisme, Katholieke Universiteit Leuven, B-3001 Heverlee, Belgium;
National Laboratory of Solid State Microstructures and Department of Physics, Nanjing University, Nanjing 210093;
