A research team, led by Ryo Shimano of the University of Tokyo, has explored ultrafast spin dynamics in the antiferromagnetic Weyl semimetal Mn₃Sn, providing direct visualization of current-induced switching processes at the sub-nanosecond scale. Mn₃Sn is of particular interest for spintronic applications due to its non-collinear spin structure, which gives rise to distinct magnetic and electrical properties at room temperature.
Using spatiotemporally resolved magneto-optical Kerr effect imaging with electrical pulses as short as 140 picoseconds, the team captured the evolution of magnetic domains during switching in polycrystalline Mn₃Sn films. The measurements revealed two distinct regimes of magnetization reversal depending on the intensity and duration of the applied current pulse: a non-thermal process where switching occurs without disrupting the antiferromagnetic order, and a thermally assisted process involving transient heating beyond the magnetic ordering temperature.
These observations clarify the long-standing question of whether the switching mechanism in Mn₃Sn is dominated by current-driven effects or thermal excitation. The identification of a non-thermal switching regime indicates that the material can support electronic manipulation of spin states on picosecond timescales, a property favorable for high-speed spintronic operation.
While the temporal resolution of the present setup is limited by the available pulse width, the findings suggest that Mn₃Sn may accommodate even faster dynamics under optimized experimental conditions. This work advances understanding of ultrafast magnetization processes in antiferromagnetic materials and establishes Mn₃Sn as a model system for exploring the limits of current-induced spin control.