Regensburg 2025 – scientific programme

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MA: Fachverband Magnetismus

MA 23: Focus Session: Magneto-Transport and Magneto-Optics of Higher Orders in Magnetization I

MA 23.9: Invited Talk

Wednesday, March 19, 2025, 12:30–13:00, H20

Ultrafast Néel order dynamics detected by time-resolved magneto-optical Voigt effect — •Haibin Zhao — Fudan University, Shanghai, China

The time-resolved magneto-optical (MO) Voigt effect can be principally utilized to study the Néel order dynamics in antiferromagnetic (AFM) materials. In this talk, I will present the quench of AFM order by ultrafast laser pulses in both collinear and noncollinear AFM spin configurations in antiferromagnets with negligible net magnetization probed by the time-resolved MO Voigt effect. For CoO with collinear spin configuration, the quench time of Néel order slows down pronouncedly near the Néel temperature (TN). In contrast, for Mn3Sn with an inverse triangular spin structure, The AFM order quench time shows negligible change with increasing temperature approaching the TN. This atypical behavior can be explained by the influence of weakened Dzyaloshinskii-Moriya interaction rather than the smaller exchange splitting on the diminished AFM order near TN. The temperature-insensitive ultrafast spin manipulation can pave the way for high-speed spintronic devices either working at a wide range of temperature or demanding spin switching near TN. The modulated Voigt angle in Mn3Sn is significantly larger than the polarization rotation due to the crystal-structure related linear dichroism effect and the modulated MO Kerr angle arising from the ferroic ordering of cluster magnetic octupole.

Keywords: Magneto-optical Voigt effect; antiferromagnetic spin; ultrafast laser; time-resovled; dynamics