Effect of magnetic anisotropy on spin-current driven by resonant dynamics of skyrmion lattices Seno Aji (a*), Muhammad Anin Nabail Azhiim (a), Nur Ika Puji Ayu (a), Adam Badra Cahaya (a), Koichi Kusakabe (b), and Muhammad Aziz Majidi (a)
a) Department of Physics, Faculty of Mathematics and Natural Sciences, Universitas Indonesia, Depok 16424, Indonesia
*senji77[at]sci.ui.ac.id
b) School of Science, Graduate School of Science, University of Hyogo, 3-2-1 Kouto, Kamigori-cho, Ako-gun, Hyogo, 678-1297, Japan
Abstract
We study the generation of spin currents in a skyrmion-hosting material lacking inversion symmetry through a microwave-driven resonance mechanism. We analyze the roles of magnetic anisotropy and polarized microwaves using micromagnetic simulation. Our results reveal two distinct skyrmion phases, designated as SkX type-I and SkX type-II, that emerge at low (Kz < 0.1 meV) and high (Kz > 0.1 meV) magnetic anisotropy, respectively. These two phases exhibit fundamentally different spin dynamics. In SkX type-I, the resonant frequency of the breathing mode lies between the clockwise and counterclockwise gyration modes of Bloch-type skyrmions at very low anisotropy and crosses over the counterclockwise mode at Kz ~ 0.04 meV. In contrast, SkX type-II exhibits unique excitation characteristics, notably the absence of the clockwise mode, while counterclockwise modes persist at both low and high frequencies. This highlights the important roles of magnetic anisotropy on spin dynamics. Moreover, the induced spin excitations generate spin currents with unconventional characteristics under polarized microwave excitation. Specifically, low-energy in-plane excitation produces strongly enhanced spin currents under left-handed circularly polarized microwaves, but these currents are suppressed when right-handed circular polarization is applied, regardless of the sign of the Dzyaloshinskii-Moriya interaction. These findings may provide new insights into the complex interplay between magnetic anisotropy and microwave polarization in resonantly driven spin-current generation.
