Abstract :
Antiferromagnetic (AFM) materials have traditionally been regarded as insensitive to magnetic perturbations, serving mainly as supporting materials in spin valve cells. However, recent studies have highlighted the potential advantages of AFM materials, including ultrafast spin dynamics and zero stray fields. We investigate whether spin-orbit torque (SOT) generated by heavy metals can modify the orientation of the AFM Néel vector or thermal contribution dominates. Based on a theoretical approach of the Néel vector dynamic equation of motion derived from the LLG equation, we extend the analytical model to the case with uniaxial anisotropy. Experiments were conducted using NiPS3/Pt heterostructures. NiPS3, a variant of transition metal dichalcogenides, is a two-dimensional van der Waals material in which Ni ions form a honeycomb lattice, with the a-axis aligned along the zigzag direction. The spins of the Ni ions are collinear and lie close to the a-axis, forming ferromagnetic spin chains with antiferromagnetic inter-chain alignment. To investigate these samples, we employed second harmonic Hall voltage measurements using a lock-in amplifier. Photoluminescence (PL) emission from NiPS3 has been reported to be spin-correlated, enabling optical determination of the Néel vector. The mechanism behind the ultra-sharp polarized PL signals in NiPS3, which do not appear in FePS3, MnPS3, remains to be clarified.