Mechanisms of FMR line broadening in CoFeB-LiNbO3 granular films in the vicinity of metal-insulator transition

JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS

卷:495

Article

Drovosekov, A. B.¹  Kreines, N. M.¹  Barkalova, A. S.^1,2  Nikolaev, S. N.³  Rylkov, V. V.^3,4,5  Sitnikov, A., V⁶ 

[1] RAS, PL Kapitza Inst Phys Problems, Moscow 119334, Russia

[2] Natl Res Univ Higher Sch Econ, Moscow 101000, Russia

[3] Natl Res Ctr, Kurchatov Inst, Moscow 123182, Russia

[4] RAS, Kotelnikov Inst Radio Engn & Elect, Fryazino 141190, Moscow Region, Russia

[5] RAS, Inst Theoret & Appl Electrodynam, Moscow 127412, Russia

[6] Voronezh State Tech Univ, Voronezh 394026, Russia

关键词: Granular films;    Metal-insulator transition;    Ferromagnetic resonance;    FMR linewidth;   

DOI  :  10.1016/j.jmmm.2019.165875

来源: Elsevier

【 摘 要 】

Metal-insulator (CoFeB)(x)(LiNbO3)(100-x), nanocomposite films with different content of the ferromagnetic (FM) phase x are investigated by ferromagnetic resonance (FMR) technique. A strong change of the FMR line shape is observed in the vicinity of metal-insulator transition (MIT) of the film, where the hopping-type conductivity sigma modifies to the regime of a strong intergranular tunnelling, characterized by a logarithmic dependence sigma(T) at high temperatures. It is shown that below MIT, the FMR linewidth is mainly determined by the inhomogeneous distribution of the local anisotropy axes in the film plane. Above MIT, the contribution of this inhomogeneity to the line broadening decreases. At the same time, two-magnon magnetic relaxation processes begin to play a significant role in the formation of the linewidth. The observed behaviour indicates the critical role of interparticle exchange in the tunnelling regime above MIT of the nanocomposite.

【 授权许可】

Free