1. Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
2. Condensed Matter Physics and Material Science Department, Brookhaven National Laboratory, Upton, New York 11973-5000, USA
3. Physics Department and National High Magnetic Field Laboratory, Florida State University, Tallahassee, Florida 32310, USA
4. Center for Ultrafast Science and Technology, Key Laboratory for Laser Plasmas(Ministry of Education), School of Physics and Astronomy, Collaborative Innovation Center of IFSA(CICIFSA), Shanghai Jiao Tong University, Shanghai 200240, China