講演情報
[21a-C501-3]Spin current generated in collinear antiferromagnet RuO2 with triple-domain structure
〇Anh ThiVan Nguyen1,2, Thi Ngoc Huyen Vu3, Yoshiaki Saito2, Samik DuttaGupta1,5,6, Hiroshi Naganuma1,2, Shoji Ikeda1,2, Tetsuo Endoh1,2,4,5 (1.CSIS, Tohoku Univ., 2.CIES, Tohoku Univ., 3.IMR, Tohoku Univ., 4.GSE, Tohoku Univ., 5.RIEC, Tohoku Univ., 6.SINP, India)
キーワード：
spin-split effect、collinear antiferromagnet、RuO2
Being one of the recent emergent interesting transition metal oxides, collinear antiferromagnet RuO2 shows an anisotropic spin-split band structure that enables the spin current generation when a charge current is applied. As a result, the spin-orbit torque (SOT) induced magnetization switching in RuO2/ferromagnetic bilayer could be attributed to not only the conventional spin Hall effect (SHE) but also the spin-split effect (SSE) [1, 2]. However, a detailed investigation of the effective spin-orbit torque (SOT) fields including the Slonczewski-like term (H_SL) and field-like term (H_FL) is lacking [2-4], and the origin of SOT fields has not been clearly analyzed yet [3, 4]. Herein, we investigate the effective SOT fields (H_SL, H_FL) and explain their origins in a RuO2/Co-Fe-B bilayer by harmonic Hall measurement. RuO2(4nm)/Co20Fe60B20 (1.2 nm) bilayer was fabricated on an α-Al2O3(0001) substrate by DC/RF sputtering, where the RuO2 (100) film was grown on the substrate with a 120-degree-tilted triple-domain-structure following the epitaxial relationship: RuO2[010]//α-Al2O3 [11-20], [-2110], [1-210]. The harmonic Hall measurement was performed for Hall bar devices of RuO2/Co-Fe-B under both configurations that Jc was parallel to [1-100] and [11-20] of the substrate. The current density (Jc) dependence of H_SL, and H_FL, evaluated from the second harmonic signal, are shown. Both H_SL and H_FL increase with Jc, implying their current-induced origin. The close values of |H_SL| and |H_FL| for both cases at the corresponding values of current density were observed, which is consistent with the suggestion from our symmetry analysis of the spin Hall conductivity tensor of RuO2 (100) with this triple-domain structure. This result revealed that the SOT in this system originated from both SSE and SHE, and the SSE plays a significant role in the SOT. This result would be important for further research on the current-induced magnetization switching using antiferromagnets.