Strain-Mediated Lattice Reconstruction Enhances Ferromagnetism in Cr₂Ge₂Te₆/WTe₂ van der Waals Heterobilayers

Van der Waals (vdW) heterostructures enable tailored electronic and magnetic phases by stacking atomically thin layers with pristine interfaces. Here, we investigate fully 2D Cr₂Ge₂Te₆/WTe₂ heterostructures and identify a strong enhancement of ferromagnetism in Cr₂Ge₂Te₆ (CGT). Magnetotransport measurements across multiple devices with WTe₂ thicknesses ranging from monolayer to bulk reveal a robust anomalous Hall effect together with a more than two fold increase of the Curie temperature and substantially enhanced coercive fields. Interface microscopy confirms chemically abrupt vdW interfaces with no detectable interdiffusion, while control experiments rule out processing- or stray-field-induced artifacts. Our experiments and theoretical calculations demonstrate that interfacial charge transfer renders CGT conductive and that proximity-induced lattice distortions in CGT enhance exchange and magnetocrystalline anisotropy. These results establish strain-mediated lattice reconstruction as a strategy for engineering high-temperature magnetic order in 2D heterostructures and clarify that modifications within the magnetic layer itself can govern proximity effects in vdW stacks.