[1] North Minzu Univ, Sch Elect & Informat Engn, Microelect & Solid State Elect Device Res Ctr, Yinchuan 750021, Peoples R China
[2] Changzhou Univ, Sch Microelect & Control Engn, Changzhou 213164, Peoples R China
[3] Lanzhou Univ Technol, Sch Sci, Dept Phys, Lanzhou 730050, Peoples R China
[4] Anshan Normal Univ, Sch Phys Sci & Technol, Anshan 114056, Peoples R China
[5] Lanzhou Univ, Minist Educ, Key Lab Magnetism & Magnet Mat, Lanzhou 730000, Peoples R China