Electron-Magnon Coupling Mediated Magnetotransport in Antiferromagnetic van der Waals Heterostructure

Electron-magnon coupling reveals key insights into the interfacial properties between non-magnetic metals and magnetic insulators, influencing charge transport and spin dynamics. Here, we present temperature-dependent Raman spectroscopy and magneto-transport measurements of few-layer graphene (FLG)/antiferromagnetic FePS${}_3$ heterostructures. The magnon mode in FePS${}_3$ softens below 40 K, and effective magnon stiffness decreases with cooling. Magnetotransport measurements show that FLG exhibits negative magnetoresistance (MR) in the heterostructure at low fields ($\pm 0.2\text{T}$), persisting up to 100 K; beyond this, MR transitions to positive. Notably, as layer thickness decreases, the coupling strength at the interface reduces, leading to a suppression of negative MR. Additionally, magnetodielectric measurements in the FLG/FePS${}_3$/FLG heterostructure show an upturn at temperatures significantly below ($T_{\text{N}}$), suggesting a role for the magnon mode in capacitance, as indicated by hybridization between magnon and phonon bands in pristine FePS${}_3$ $\mathit{\text{via}}$ magnetoelastic coupling.