Giant anisotropic Gilbert damping versus isotropic ultrafast demagnetization in monocrystalline Co50Fe50 films

H. Xia, Z. R. Zhao, F. L. Zeng, H. C. Zhao, J. Y. Shi, Z. Zheng, X. Shen, J. He, G. Ni, Y. Z. Wu, L. Y. Chen, and H. B. Zhao
Phys. Rev. B 104, 024404 – Published 2 July 2021

Abstract

The magnetization orientation dependence of Gilbert damping and ultrafast demagnetization were investigated in single-crystalline Co50Fe50 films grown on a MgO(100) substrate by the time-resolved magneto-optical Kerr effect technique. The intrinsic Gilbert damping coefficient extracted from the time evolution of magnetization precessions shows a remarkably large anisotropy with a ratio of more than 300% for magnetization orientations along the 100 and 110 axes. Such a large anisotropy of Gilbert damping persists to high frequencies up to 50GHz, where the effect of two-magnon scattering is suppressed. In contrast to the anisotropic Gilbert damping, the ultrafast demagnetization time and ratio for different in-plane magnetization orientations are nearly isotropic with the magnetization orientation. Although anisotropic Gilbert damping can be explained by the variation of spin-orbit coupling with the magnetization orientations, our results demonstrate that the role of spin-orbit coupling in the high nonequilibrium state after ultrafast laser excitation is isotropic in driving ultrafast spin-flip processes.

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  • Received 22 February 2021
  • Revised 5 June 2021
  • Accepted 24 June 2021

DOI:https://doi.org/10.1103/PhysRevB.104.024404

©2021 American Physical Society

Physics Subject Headings (PhySH)

Condensed Matter, Materials & Applied Physics

Authors & Affiliations

H. Xia1,2, Z. R. Zhao2, F. L. Zeng1, H. C. Zhao2, J. Y. Shi2, Z. Zheng2, X. Shen1, J. He2, G. Ni2, Y. Z. Wu1,3,*, L. Y. Chen2, and H. B. Zhao2,†

  • 1Department of Physics, State Key Laboratory of Surface Physics, Fudan University, Shanghai 200433, China
  • 2Key Laboratory of Micro and Nano Photonic Structures (Ministry of Education), and Shanghai Ultra-precision Optical Manufacturing Engineering Research Center, Department of Optical Science and Engineering, Fudan University, Shanghai 200433, China
  • 3Shanghai Research Center for Quantum Sciences, Shanghai 201315, China

  • *wuyizheng@fudan.edu.cn
  • hbzhao@fudan.edu.cn

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Issue

Vol. 104, Iss. 2 — 1 July 2021

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