Photovoltaic Modulation of Magneto-Transport in Fe ₃ GeTe ₂ /n-Si van der Waals Heterostructures via Interfacial Photoelectron Transfer

Conventional voltage- or current-driven spintronic devices suffer from high power consumption and integration challenges, necessitating the development of alternative, energy-efficient pathways for spin control. Here, we demonstrate a photovoltaic tunable h-BN/Fe3GeTe2 (FGT)/n-Si magnetic heterostructure, exhibiting a reversible suppression of ∼25% in saturation magnetization (MS) near the Curie temperature. At 140 K, continuous illumination switches the FGT layer from a ferromagnetic to a paramagnetic state, demonstrating the effectiveness of photovoltaic control over the magnetic order. First-principles calculations reveal that photogenerated electrons in the n-Si are injected into the adjacent FGT layer, partially occupying minority-spin Fe-3d orbitals at a doping level of 0.1 electrons per atom, thereby reducing the total magnetic moment by 5–10% and weakening spin polarization and ferromagnetic exchange. Time-resolved Hall measurements confirm excellent cycling stability and reversibility of this modulation. This work integrates photovoltaic devices with emerging 2D magnetic materials, unlocking sunlight-tunable magnetic memory and CMOS-compatible spin-logic architectures, and offering a pathway toward ultralow-power, optically programmable spintronics.