Quantum Condensed Matter Division, Oak Ridge National Laboratory, Oak Ridge 37831, USA;
Department of Physics and Astronomy, University of Kentucky, Lexington 40506, USA;
Department of Physics, Renmin University of China, Beijing 100872;
Quantum Condensed Matter Division, Oak Ridge National Laboratory, Oak Ridge 37831, USA;
Quantum Condensed Matter Division, Oak Ridge National Laboratory, Oak Ridge 37831, USA;
Quantum Condensed Matter Division, Oak Ridge National Laboratory, Oak Ridge 37831, USA;
Department of Physics, Zhejiang University, Hangzhou 310027;
Department of Physics, Zhejiang University, Hangzhou 310027;