講演情報
[14p-K303-2]Effect of additive element on light-helicity induced magnetization dynamics
in Co1-xYx (Y = Pt, Pd, Ni) alloy
〇抜井 康起1,2、飯浜 賢志3、石橋 一晃1,2、水上 成美2,4 (1.東北大工、2.東北大AIMR、3.名大工、4.東北大CSIS)
キーワード：
spintronics、circularly polarized light、orbitronics
Magnetization control using light has drawn considerable attention for diverse magnetic applications, including laser-assisted magnetic recording and optically writable spintronic memory [1]. Among these, helicity-dependent all-optical switching (HD-AOS) enables direct manipulation of ferromagnetic metal magnetization by tuning the helicity of incident light [2]. Although multiple mechanisms have been proposed for HD-AOS, accumulating evidence suggests that light-induced effective magnetic fields and spin polarization exert both field- and damping-like torques on magnetization [3,4]. More recently, our group reported that electron orbitals can also be generated by light helicity, as demonstrated by time-resolved magneto-optical Kerr effect (TRMOKE) measurements of CoPt alloy thin films [5].In this study, we systematically investigate light-helicity-induced magnetization dynamics in Co1−xYx (Y = Pt, Pd, Ni) thin films. These samples were grown on thermally oxidized Si substrates via ultrahigh vacuum magnetron sputtering, with compositions finely tuned by co-sputtering. We conducted TRMOKE measurements under a 2 T in-plane magnetic field, observing magnetization precession initiated by circularly polarized pump pulses. Figure 1(a) shows a representative waveform from Co-Pt alloy films, fitted with a damped sinusoidal function to derive the oscillation amplitude A and phase φ. Figure 1(b) plots φ against x, revealing a clear increase in φ with x, which points to a damping-like torque arising from helicity-driven orbital generation. Further details of these findings and the underlying physics will be discussed in our presentation.This work was partially supported by JSPS KAKENHI, JST PRESTO, MEXT X-NICS, the Asahi Glass Foundation, and the Murata Science Foundation. K.N. and K.I. gratefully acknowledge the support of GP-spin at Tohoku University.