中国物理B ›› 2018, Vol. 27 ›› Issue (5): 57501-057501.doi: 10.1088/1674-1056/27/5/057501

• CONDENSED MATTER: ELECTRONIC STRUCTURE, ELECTRICAL, MAGNETIC, AND OPTICAL PROPERTIES • 上一篇    下一篇

Interfacial effect on the reverse of magnetization and ultrafast demagnetization in Co/Ni bilayers with perpendicular magnetic anisotropy

Zi-Zhao Gong(弓子召), Wei Zhang(张伟), Wei He(何为), Xiang-Qun Zhang(张向群), Yong Liu(刘永), Zhao-Hua Cheng(成昭华)   

  1. 1 State Key Laboratory of Metastable Materials Science & Technology and Key Laboratory for Microstructural Material Physics of Hebei Province, School of Science, Yanshan University, Qinhuangdao 066004, China;
    2 State Key Laboratory of Magnetism and Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China;
    3 School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 100190, China
  • 收稿日期:2018-02-04 修回日期:2018-03-13 出版日期:2018-05-05 发布日期:2018-05-05
  • 通讯作者: Yong Liu, Zhao-Hua Cheng E-mail:ycliu@ysu.edu.cn;zhcheng@iphy.ac.cn
  • 基金资助:
    Project supported by the National Basic Research Program of China (Grant Nos.2015CB921403 and 2016YFA0300701),the National Natural Science Foundation of China (Grant Nos.91622126,51427801,and 51671212),and the Natural Science Foundation of Hebei Province,China (Grant No.A2015203021).

Interfacial effect on the reverse of magnetization and ultrafast demagnetization in Co/Ni bilayers with perpendicular magnetic anisotropy

Zi-Zhao Gong(弓子召)1,2, Wei Zhang(张伟)2,3, Wei He(何为)2, Xiang-Qun Zhang(张向群)2, Yong Liu(刘永)1, Zhao-Hua Cheng(成昭华)2,3   

  1. 1 State Key Laboratory of Metastable Materials Science & Technology and Key Laboratory for Microstructural Material Physics of Hebei Province, School of Science, Yanshan University, Qinhuangdao 066004, China;
    2 State Key Laboratory of Magnetism and Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China;
    3 School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 100190, China
  • Received:2018-02-04 Revised:2018-03-13 Online:2018-05-05 Published:2018-05-05
  • Contact: Yong Liu, Zhao-Hua Cheng E-mail:ycliu@ysu.edu.cn;zhcheng@iphy.ac.cn
  • Supported by:
    Project supported by the National Basic Research Program of China (Grant Nos.2015CB921403 and 2016YFA0300701),the National Natural Science Foundation of China (Grant Nos.91622126,51427801,and 51671212),and the Natural Science Foundation of Hebei Province,China (Grant No.A2015203021).

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摘要： For static magnetic properties of the Co/Ni bilayers, macroscopic hysteresis loops and microscopic magnetic moment distributions have been determined by the object oriented micromagnetic framework (OOMMF). It is found that when the bilayer systems are fully decoupled, the magnetizations of the two phases reverse separately. The coercivity of the bilayers decreases to a valley value sharply with increasing interfacial exchange coupling and then rises slowly to a platform. On the other hand, we have carried out an atomistic simulation for the laser-induced ultrafast demagnetization of the Co/Ni bilayer. A larger damping constant leads to a faster demagnetization as well as a larger degree of demagnetization, which is consistent with the first-principle theoretical results. For the magnetization recovery process, the damping constant has different influences on the recovery time with various peak electron temperatures, which is ignored in previous atomistic simulations as well as the Landau-Liftshit-Bloch (LLB) micromagnetic calculations. Furthermore, as the interfacial exchange coupling increases, the ultrafast demagnetization curves for Co and Ni become coincident, which is a demonstration for the transition from two-phase phenomenon to single-phase phenomenon.

关键词: micromagnetic simulation, interfacial effect, hysteresis loops, ultrafast demagnetization

Abstract: For static magnetic properties of the Co/Ni bilayers, macroscopic hysteresis loops and microscopic magnetic moment distributions have been determined by the object oriented micromagnetic framework (OOMMF). It is found that when the bilayer systems are fully decoupled, the magnetizations of the two phases reverse separately. The coercivity of the bilayers decreases to a valley value sharply with increasing interfacial exchange coupling and then rises slowly to a platform. On the other hand, we have carried out an atomistic simulation for the laser-induced ultrafast demagnetization of the Co/Ni bilayer. A larger damping constant leads to a faster demagnetization as well as a larger degree of demagnetization, which is consistent with the first-principle theoretical results. For the magnetization recovery process, the damping constant has different influences on the recovery time with various peak electron temperatures, which is ignored in previous atomistic simulations as well as the Landau-Liftshit-Bloch (LLB) micromagnetic calculations. Furthermore, as the interfacial exchange coupling increases, the ultrafast demagnetization curves for Co and Ni become coincident, which is a demonstration for the transition from two-phase phenomenon to single-phase phenomenon.

Key words: micromagnetic simulation, interfacial effect, hysteresis loops, ultrafast demagnetization

中图分类号:  (Magnetization reversal mechanisms)

  • 75.60.Jk
75.78.-n (Magnetization dynamics) 75.70.Cn (Magnetic properties of interfaces (multilayers, superlattices, heterostructures)) 75.78.Cd (Micromagnetic simulations ?)