講演情報
[25a-P01-23]Time-resolved magneto-optical Kerr effect for antiferromagnetic Mn3Sn films with perpendicular magnetic anisotropy
〇(D)Zaizhou Jin1,2, Tomohiro Uchimura1,3, Satoshi Iihama4,2, Yuta Yamane4,3, Junta Igarashi5, Shunsuke Fukami3,6,2, Shigemi Mizukami2,6 (1.Tohoku Univ., 2.AIMR, Tohoku Univ., 3.RIEC, Tohoku Univ., 4.FRIS, Tohoku Univ., 5.Univ. of Lorraine, 6.CSIS, Tohoku Univ.)
キーワード：
magneto-optical Kerr effect、ultrafast spin dynamics、chiral antiferromagnetic
Non-collinear chiral antiferromagnet (AFM) Mn3Sn is an attractive material since this AFM shows the Néel temperature, 420 K and non-negligible magneto-optical Kerr effect (MOKE) due to magnetic-octupole order and topological Weyl nature. Despite extensive research on ultrafast magnetization dynamics in ferromagnets and ferrimagnets, investigations into such chiral AFMs are still in their very early stages. In particular, magnetic damping significantly influences both the energy efficiency and operational speed of the device aiming to utilize the electronic spin degree of freedom, thus further understanding is demanded. Here we investigate, for the first time, time-resolve magneto-optical Kerr effect for Mn3Sn films with a perpendicular magnetic anisotropy to gain insight into the physics of octupole dynamics. The films were prepared using magnetron sputtering technique. Film stacking structure is single crystalline MgO (110) sub./W(2) /Ta(3) /Mn3Sn(30) /MgO(1.3) /Ru(1) (thickness is in nm). The time-resolved MOKE (TR-MOKE) was measured using all-optical pump-probe technique. For measurement configuration, where the applied magnetic field is parallel to the film normal. The out-of-plane magnetic-octupole dynamics is induced by the pump laser pulse and is detected via MOKE for a probe laser pulse. Typical TRMOKE data, in which magnetic signal was extracted by taking difference of signals measured with applied positive/negative magnetic field. We observed ultrafast change of Kerr rotation angle at the zero delay, which is attributed to ultrafast reduction of magnetic octupole order. We also observed the damped-oscillation which would be attributed to GHz-frequency magnetic octupole order dynamics. We will discuss more details in the presentation.