[Lu, Zhendong; Luo, Xiao-Qing; Liu, Qin-Ke; Luo, XQ; Zhou, Yaojie; Wang, Xin-Lin] Univ South China, Sch Elect Engn, Hengyang 421001, Peoples R China.
[Li, Yan] Univ South China, Sch Nucl Sci & Technol, Hengyang 421001, Peoples R China.
[Liu, W. M.] Chinese Acad Sci, Inst Phys, Beijing Natl Lab Condensed Matter Phys, Beijing 100190, Peoples R China.
[Wang, Xin-Lin] Univ South China, Sch Mech Engn, Hunan Prov Key Lab Ultrafast Micro Nano Technol &, Hengyang 421001, Peoples R China.