[20a-131-1~11] 【CS.9】 Code-sharing Session of 10.1, 10.2, 10.3 & 10.4

▲ [20a-131-9] Brownian motion of skyrmions in Ta|Fe₇₂Co₈B₂₀|TaO_x

〇Yuma Jibiki¹, Minori Goto^1,2, Titiksha Srivastava³, Willy Lim³, Stephane Auffret³, Claire Baraduc³, Helene Bea³, Jaehun Cho^1,2, Eiiti Tamura^1,2, Yoshishige Suzuki^1,2 (1.Osaka Univ., 2.Osaka CSRN, 3.Institute of Engineering Univ. Grenoble Alpes)

Keywords:spintronics, skyrmion

Magnetic skyrmion has topologically stable spin texture. For formation of the magnetic skyrmion, it is important to control energy balance between magnetic anisotropy, exchange interaction and Dyzaloshinskii-Moriya interaction. It has been found that skyrmion at room temperature can be fabricated by adjusting the energy balance [1] and shows Brownian motion by thermal excitation [2]. By using the skyrmion, realization of the ultra-low power consumption device like the Brownian computing is expected. In this research, we focus on the Brownian motion of skyrmion and evaluate its diffusion coefficient.The film stack was Ta(3 nm)|Fe72Co8B20(0.9-1.3 nm)|TaOx(0.5-0.9 nm)|Al(0.5 nm) deposited on SiO2 substrate by sputtering methods. Figure 1 shows the picture of skyrmions (black dots) under perpendicular magnetic field taken by Kerr microscope. The observed skyrmion size, which depends on Fe72Co8B20 and TaOx oxidation state, is about 0.5 to 1.5 µm. Figure 2 is the mean-squared displacement (R2) of two dimensional skyrmions motion as a function of moving time. The inset shows trajectories of selected skyrmions at room temperature. The mean-squared displacement is fitted by a linear function (red dots line) to evaluate the diffusion coefficient. We also evaluated the diffusion coefficient of one dimensional motion of skyrmions on a wire. We report the difference between one and two dimensional Brownian motions. This research was supported by MIC.