[19p-P06-1~50] 10 Spintronics and Magnetics (Poster)

English Presentation

[19p-P06-27] Dynamic magnetic properties in RuO₂/Co-Fe-B stack film

〇Anh ThiVan Nguyen^1,2, Yoshiaki Saito², Hiroshi Naganuma^1,2, Duong Vu³, Shoji Ikeda^1,2, Tetsuo Endoh^1,2,4,5 (1.CSIS, Tohoku Univ., 2.CIES, Tohoku Univ., 3.IoP, VAST, 4.ECEI, Tohoku Univ., 5.RIEC, Tohoku Univ.)

Keywords:

Altermagnetic RuO2,Dynamic magnetic properties,Damping constant

Spin-split effect-induced spin current generation in altermagnetic RuO2 [1, 2] has been attractive for potential applications in spintronics devices such as spin-orbit torque magnetic random-access memory (SOT-MRAM) [3]. Recent works have reported SSE-induced SOT in RuO2/Ferromagnetic bilayers with various crystal orientations [2, 4]. However, a detailed study on the dynamic magnetic properties, such as the damping constant (a) and effective magnetization (4pMs,eff) in these stacking structures has not been reported. Herein we choose the stacking structures consisting of RuO2and Co-Fe-B and investigate the Co-Fe-B layer’s thickness (t_CFB) and RuO2 layer thickness (t_RuO2) dependence of a and 4pMs,eff by a broadband ferromagnetic resonance (FMR) measurement technique.RuO2(t_RuO2)/Co-Fe-B (t_CFB)/MgO (1.3 nm)/Ta (1.0 nm) stacking structures were fabricated on an aAl2O3(0001) substrate by DC/RF sputtering. The RuO2 (100) film was grown on the substrate by RF sputtering at 300oC, while other layers were prepared at room temperature. Each stacking film possesses an in-plane magnetic anisotropy. Figures 1 (a) and (b) show t_CFB and t_RuO2 dependences of a for the stacking films evaluated from the FMR spectra measured in the field and frequency domains. a increases with the decrease of t_CFB. For a stack film with t_CFB = 10 nm, a = 0.0056 which is close to the bulk value of a Co-Fe-B [5]. Then a increases to 0.022 when t_CFB reduces to 1.2 nm. The increase of a might be attributed to the spin pumping, and/or the magnetic inhomogeneity such as the anisotropy dispersion, and/or the two-magnon scattering, and so on. On the other hand, a is around 0.008 and is almost saturated at t_RuO2 range above 1 nm, which suggests that using RuO2 would enable the retention of a low a value in a wide range of the RuO2 thickness. The results would be helpful for the on-going research and application of altermagnet-based spintronics.