[1] Southeast Univ, Sch Phys, Key Lab Quantum Mat & Devices, Minist Educ, Nanjing 211189, Peoples R China
[2] Northwestern Polytech Univ, Sch Microelect, Xian 710072, Peoples R China
[3] Nanjing Univ, Natl Lab Solid Microstruct, Nanjing 210093, Peoples R China
[4] Univ Paris Saclay, CNRS, CEA, CEA Saclay,SPEC, Gif Sur Yvette F-91191, France
[5] Synchrotron SOLEIL, Lorme Merisiers, St Aubin BP 48, F-91192 Gif Sur Yvette, France
[6] Natl Univ Singapore, Dept Phys, 2 Sci Dr 3, Singapore 117551, Singapore
[7] Natl Univ Singapore, Ctr Adv 2D Mat, 6 Sci Dr 2, Singapore 117546, Singapore
[8] Univ Lorraine, CNRS, UMR 7198, Inst Jean Lamour, Nancy, France