[1] Tongji Univ, Shanghai Key Lab Special Artificial Microstruct M, Shanghai 200092, Peoples R China
[2] Tongji Univ, Sch Phys Sci & Engn, Shanghai 200092, Peoples R China
[3] Lanzhou Univ, Minist Educ, Key Lab Magnetism & Magnet Mat, Lanzhou 730000, Gansu, Peoples R China