中国物理B ›› 2015, Vol. 24 ›› Issue (7): 77505-077505.doi: 10.1088/1674-1056/24/7/077505

所属专题: TOPICAL REVIEW — Magnetism, magnetic materials, and interdisciplinary research

• SPECIAL TOPIC --- Non-equilibrium phenomena in soft matters • 上一篇    下一篇

Manipulating magnetic anisotropy and ultrafast spin dynamics of magnetic nanostructures

成昭华, 何为, 张向群, 孙达力, 杜海峰, 吴琼, 叶军, 房亚鹏, 刘郝亮   

  1. State Key Laboratory of Magnetism, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
  • 收稿日期:2015-04-15 出版日期:2015-07-05 发布日期:2015-07-05
  • 基金资助:

    Project supported by the National Basic Research Program of China (Grant Nos. 2015CB921403, 2011CB921801, and 2012CB933101) and the National Natural Science Foundation of China (Grant Nos. 51427801, 11374350, 51201179, and 11274361).

Manipulating magnetic anisotropy and ultrafast spin dynamics of magnetic nanostructures

Cheng Zhao-Hua (成昭华), He Wei (何为), Zhang Xiang-Qun (张向群), Sun Da-Li (孙达力), Du Hai-Feng (杜海峰), Wu Qiong (吴琼), Ye Jun (叶军), Fang Ya-Peng (房亚鹏), Liu Hao-Liang (刘郝亮)   

  1. State Key Laboratory of Magnetism, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
  • Received:2015-04-15 Online:2015-07-05 Published:2015-07-05
  • Contact: Cheng Zhao-Hua E-mail:zhcheng@iphy.ac.cn
  • Supported by:

    Project supported by the National Basic Research Program of China (Grant Nos. 2015CB921403, 2011CB921801, and 2012CB933101) and the National Natural Science Foundation of China (Grant Nos. 51427801, 11374350, 51201179, and 11274361).

摘要:

We present our extensive research into magnetic anisotropy. We tuned the terrace width of Si(111) substrate by a novel method: varying the direction of heating current and consequently manipulating the magnetic anisotropy of magnetic structures on the stepped substrate by decorating its atomic steps. Laser-induced ultrafast demagnetization of a CoFeB/MgO/CoFeB magnetic tunneling junction was explored by the time-resolved magneto-optical Kerr effect (TRMOKE) for both the parallel state (P state) and the antiparallel state (AP state) of the magnetizations between two magnetic layers. It was observed that the demagnetization time is shorter and the magnitude of demagnetization is larger in the AP state than those in the P state. These behaviors are attributed to the ultrafast spin transfer between two CoFeB layers via the tunneling of hot electrons through the MgO barrier. Our observation indicates that ultrafast demagnetization can be engineered by the hot electron tunneling current. This opens the door to manipulate the ultrafast spin current in magnetic tunneling junctions. Furthermore, an all-optical TR-MOKE technique provides the flexibility for exploring the nonlinear magnetization dynamics in ferromagnetic materials, especially with metallic materials.

关键词: magnetic anisotropy, ultrafast spin dynamics, magnetic nanostructures

Abstract:

We present our extensive research into magnetic anisotropy. We tuned the terrace width of Si(111) substrate by a novel method: varying the direction of heating current and consequently manipulating the magnetic anisotropy of magnetic structures on the stepped substrate by decorating its atomic steps. Laser-induced ultrafast demagnetization of a CoFeB/MgO/CoFeB magnetic tunneling junction was explored by the time-resolved magneto-optical Kerr effect (TRMOKE) for both the parallel state (P state) and the antiparallel state (AP state) of the magnetizations between two magnetic layers. It was observed that the demagnetization time is shorter and the magnitude of demagnetization is larger in the AP state than those in the P state. These behaviors are attributed to the ultrafast spin transfer between two CoFeB layers via the tunneling of hot electrons through the MgO barrier. Our observation indicates that ultrafast demagnetization can be engineered by the hot electron tunneling current. This opens the door to manipulate the ultrafast spin current in magnetic tunneling junctions. Furthermore, an all-optical TR-MOKE technique provides the flexibility for exploring the nonlinear magnetization dynamics in ferromagnetic materials, especially with metallic materials.

Key words: magnetic anisotropy, ultrafast spin dynamics, magnetic nanostructures

中图分类号:  (Magnetization dynamics)

  • 75.78.-n
75.40.Gb (Dynamic properties?) 76.50.+g (Ferromagnetic, antiferromagnetic, and ferrimagnetic resonances; spin-wave resonance) 75.70.-i (Magnetic properties of thin films, surfaces, and interfaces)