Strain-mediated magnetoelectric effect in van der Waals ferromagnetic/ferroelectric heterostructures

Recent discovery of intrinsic two-dimensional ferromagnetism in van der Waals (vdW) magnetic materials has stimulated research on the fundamental properties and spintronic applications of the materials and their heterostructures. In this investigation, we fabricated heterostructure devices, composed of two distinct families of vdW materials, and studied the interfacial interaction between the two materials. Specifically, we observe strain-mediated magnetoelectric effect in vdW ferromagnetic (FM) / ferroelectric (FE) heterostructure devices consisting of vdW FM Fe₃GeTe₂ and vdW FE α-In₂Se₃. Magneto-optical Kerr effect measurements show that gate voltages can decrease magnetic coercivity of Fe₃GeTe₂ for both positive and negative gate voltages. The change in Fe₃GeTe₂ magnetic coercivity and anisotropy is attributed to the voltage-induced strain generated from α-In₂Se₃ which is transferred to the Fe₃GeTe₂ across the vdW interface. This is confirmed by Raman spectroscopy and density functional theory calculation. Our results demonstrate an effective method to realize low-power voltage-controlled vdW spintronic devices utilizing the magnetoelectric effect in vdW FM/FE heterostructures.