Selective enhancement of the low-frequency antiferromagnetic resonance in NiO via interfacial laser-induced optical torque

Optical control of antiferromagnetic order provides a promising route toward ultrafast and low-dissipation spintronic functionalities. Laser-induced optical torque (LOT) has recently been shown as a route for controlling antiferromagnetic order in metallic antiferromagnets. Using a two-sublattice Landau–Lifshitz–Gilbert model, this article investigates the Néel-vector dynamics in a Mn2Au/NiO heterostructure, where LOT generated in Mn2Au is represented as an effective staggered driving field acting on NiO through interfacial coupling. We show that this driving couples selectively to the low-frequency, in-plane antiferromagnetic mode because its dominant effective field lies within the easy plane, while the high-frequency out-of-plane mode is only weakly affected. This symmetry-selective response produces a characteristic sin(2θ) polarization dependence. For sufficiently strong excitation, a single pulse induces deterministic 180° Néel-vector reversal, while repeated pulses enable pulse-countable switching within a finite operating window. These results provide experimentally testable signatures and suggest a route toward all-optical control of insulating antiferromagnets.