[1] Chinese Acad Sci, Inst Solid State Phys, Key Lab Mat Phys, Hefei 230031, Anhui, Peoples R China
[2] Univ Sci & Technol China, Hefei 230026, Anhui, Peoples R China
[3] Univ Wollongong, Inst Superconducting & Elect Mat, Wollongong, NSW 2522, Australia
[4] Chinese Acad Sci, High Field Magnet Lab, Hefei 230031, Anhui, Peoples R China
[5] Nanjing Univ, Collaborat Innovat Ctr Adv Microstruct, Nanjing 210093, Jiangsu, Peoples R China
[6] Univ Nebraska, Dept Phys & Astron, Lincoln, NE 68588 USA
[7] Univ Nebraska, Nebraska Ctr Mat & Nanosci, Lincoln, NE 68588 USA