We investigated the temperature dependence and mode sensitivity of antiferromagnetic (AFM) domain dynamics in nickel oxide (NiO) by time-resolved imaging of phonon-mediated changes over the temperature range from ∼300 K to ∼523 K. Resonant second-order transverse optical (2TO) and longitudinal optical (LO) phonon excitations were conducted using a mid-infrared free-electron laser. The AFM domain images were recorded using magneto-optical linear birefringence microscopy. Our experiments revealed distinct domain reconfigurations: resonant 2TO phonon excitation induced domain changes that persisted on the millisecond timescale (1.05 ± 0.03 ms) with thermally retarded recovery, whereas LO phonon excitation produced rapid microsecond recovery (80.3 ± 25.4 μs), accelerating with increasing temperature. These contrasting responses reflect mode-specific spin-phonon coupling conditions in NiO, indicating that temperature-dependent domain reconfiguration is governed by slower energy redistribution processes that extend beyond solely phonon relaxations.
Ju et al. (Tue,) studied this question.