Zaizhou Jin - Ultrafast Collapse and Dynamics of Octupole Order in Antiferromagnetic Mn3Sn Films
- Date: Dec 2, 2024
- Time: 02:00 PM - 03:30 PM (Local Time Germany)
- Location: MPI CPfS
- Room: Seminar rooms 1-2

Abstract: Non-collinear chiral antiferromagnet (AFM) Mn3Sn is an attractive material since this AFM exhibits a Néel temperature of 420 K and a 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-resolved 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. The 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 an all-optical pump-probe technique. The out-of-plane magnetic-octupole dynamics is induced by the pump laser pulse and is detected via MOKE for a probe laser pulse. We observed an ultrafast change of Kerr rotation angle at the zero delay, which is attributed to ultrafast collapse of magnetic octupole order. We also observed the damped-oscillation which would be attributed to GHz-frequency magnetic octupole order dynamics.
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