Ultrafast photo-induced turning of magnetization and its relaxation dynamics in GaMnAs  

作　　者：LUO Jing,ZHENG HouZhi,SHEN Chao,ZHANG Hao,ZHU Ke,ZHU Hui,LIU Jian,LI GuiRong,JI Yang & ZHAO JianHua State Key Laboratory for Superlattices and Microstructures,Institute of Semiconductors,Chinese Academy of Sciences,Beijing 100083,China 

出　　处：《Science China(Physics,Mechanics & Astronomy)》2010年第5期779-782,共4页中国科学：物理学、力学、天文学（英文版）

基　　金：supported by the National Basic Research Program of China (Grant Nos. 2006CB932801, 2007CB924903, and 2007CB924904);the Special Research Programs of Chinese Academy of Sciences,the Knowledge Innovation Program of Chinese Academy of Sciences (Grant No. KJCX.YW.W09);the National Natural Science Foundation of China (Grant Nos. 60836002, 10674130, and 60521001)

摘　　要：We report that,by linearly polarized pumping of different wavelengths,Kerr transients appear at zero magnetic field only in the case when GaMnAs samples are initialized at 3 K by first applying a 0.8 Tesla field and then returning to zero field.We find that,instead of magnetization precession,the near-band gap excitation induces a coherent out-of-plane turning of magnetization,which shows very long relaxation dynamics with no precession.When photon energy increases,the peak value of the Kerr transient increases,but it decays rapidly to the original slow transient seen under the near-band-gap excitation.We report that,by linearly polarized pumping of different wavelengths,Kerr transients appear at zero magnetic field only in the case when GaMnAs samples are initialized at 3 K by first applying a 0.8 Tesla field and then returning to zero field.We find that,instead of magnetization precession,the near-band gap excitation induces a coherent out-of-plane turning of magnetization,which shows very long relaxation dynamics with no precession.When photon energy increases,the peak value of the Kerr transient increases,but it decays rapidly to the original slow transient seen under the near-band-gap excitation.

关 键 词：DILUTE magnetic semiconductor magneto-crystalline anisotropy TIME-RESOLVED KERR rotation coherent PRECESSION 

分 类 号：O441.4[理学—电磁学]