Chin. Phys. B, 2020, Vol. 29(10): 107503    DOI: 10.1088/1674-1056/abad1d
 CONDENSED MATTER: ELECTRONIC STRUCTURE, ELECTRICAL, MAGNETIC, AND OPTICAL PROPERTIES Prev   Next

# Giant anisotropy of magnetic damping and significant in-plane uniaxial magnetic anisotropy in amorphous Co40Fe40B20 films on GaAs(001)

Ji Wang(王佶)1, Hong-Qing Tu(涂宏庆)1,2, Jian Liang(梁健)3, Ya Zhai(翟亚)3, Ruo-Bai Liu(刘若柏)1, Yuan Yuan(袁源)1, Lin-Ao Huang(黄林傲)1, Tian-Yu Liu(刘天宇)1, Bo Liu(刘波)4,†, Hao Meng(孟皓)4, Biao You(游彪)1,6, Wei Zhang(张维)1,6, Yong-Bing Xu(徐永兵)5, and Jun Du(杜军)1,6,
1 National Laboratory of Solid State Microstructures and Department of Physics, Nanjing University, Nanjing 210093, China
2 Department of Mathematics and Physics, Nanjing Institute of Technology, Nanjing 211167, China
3 Department of Physics and Jiangsu Key Laboratory of Advanced Metallic Materials, Southeast University, Nanjing 211189, China
4 Key Laboratory of Spintronics Materials, Devices and Systems of Zhejiang Province, Hangzhou 311300, China
5 Department of Electronic Engineering, Nanjing University, Nanjing 210093, China
6 Collaborative Innovation Center of Advanced Microstructures, Nanjing 210093, China
Abstract

Tuning magnetic damping constant in dedicated spintronic devices has important scientific and technological implications. Here we report on anisotropic damping in various compositional amorphous CoFeB films grown on GaAs(001) substrates. Measured by a vector network analyzer-ferromagnetic resonance (VNA-FMR) equipment, a giant magnetic damping anisotropy of 385%, i.e., the damping constant increases by about four times, is observed in a 10-nm-thick Co40Fe40B20 film when its magnetization rotates from easy axis to hard axis, accompanied by a large and pure in-plane uniaxial magnetic anisotropy (UMA) with its anisotropic field of about 450 Oe. The distinct damping anisotropy is mainly resulted from anisotropic two-magnon-scattering induced by the interface between the ferromagnetic layer and the substrate, which also generates a significant UMA in the film plane.

Keywords:  magnetic damping      uniaxial magnetic anisotropy      ferromagnetic resonance      two-magnon scattering
Received:  05 July 2020      Revised:  31 July 2020      Published:  05 October 2020
 PACS: 75.78.-n (Magnetization dynamics) 75.30.Gw (Magnetic anisotropy) 76.50.+g (Ferromagnetic, antiferromagnetic, and ferrimagnetic resonances; spin-wave resonance)
Corresponding Authors:  Corresponding author. E-mail: liubo@hikstor.com Corresponding author. E-mail: jdu@nju.edu.cn
 Fig. 1.  XRD patterns for the Co40Fe40B20 film samples and a pure GaAs(001) substrate. Fig. 2.  The M–H loops measured along [110] (a) and $[1\bar{1}0]$ (b) crystallographic orientations of the GaAs(001) substrate and the azimuthal dependence of remanence ratio (c) for samples S1 and S2. Fig. 3.  (a) The measurement configuration of VNA-FMR. (b) Typical VNA-FMR spectra for several selected frequencies at φH = 0°. (c) Typical VNA-FMR spectra at various azimuthal angles recorded at f = 10 GHz. (d) The experimental (square dots) and fitted (red line) in-plane azimuthal dependence of Hr at f = 10 GHz. Fig. 4.  (a) The Hr dependences of frequency at φH = 0°, 30°, 60°, 75°, 90°, (b) azimuthal dependence of ΔH at f = 10 GHz, (c) frequency dependences of ΔH at φH = 0°, 30°, 60°, 75°, 90°, and (d) azimuthal dependence of αeff for sample S1. The experimental results are shown as dots and the fitted results are shown as lines except for (b), in which the line is only guide to eyes. Table 1.  Magnetic damping constants at various azimuthal angles and the corresponding values of η in the CoFeB films with different compositions and thicknesses. The data for the Co56Fe24B20 (10 nm) and Co56Fe24B20 (20 nm) films are taken from Ref. [24].