Oral: Ultrafast All-Optical Control of Switchable Magnetization in an Antiferromagnet

The optomagnet effect observed in collinear antiferromagnetic (Fe_0.875Zn_0.125)₂Mo₃O₈ reveals a novel approach for controlling spin moments within a sub-nanosecond timescale. This mechanism provides a probability to record magnetic information via all-optical method. To assess its practicality, we develop a time-resolved pump-probe technique that employs a series of pump pulses within a nanosecond, allowing for independent control of both polarization and fluence. Our findings demonstrate that the long-lasting transient spin moments in (Fe_0.875Zn_0.125)₂Mo₃O₈ can be activated with switchable orientations by adjusting the pulse sequence with appropriate polarization and fluence. We successfully performed a write-rewrite operation within sub-nanosecond timescales by using a series of oppositely circularly polarized light. This provides a new paradigm for all-optical switching by utilizing the optomagnet effect, which has the potential for light-based memory application.