1. Department of Physics, Washington University in St Louis, St. Louis, Missouri 63130, United States
2. College of Ocean Science and Engineering, Shanghai Maritime University, Shanghai 201306, People’s Republic of China
3. Department of Physics, Nanchang University, Nanchang 330031, People’s Republic of China
4. Institute of Materials Science and Engineering, Washington University in St. Louis, St. Louis, Missouri 63130, United States