Single-Material Magnetoelectric Coupling in Transition Metal-Doped Hafnia-Based Ferroelectric Thin Films

Magnetoelectric (ME) coupling in CMOS-compatible oxides would enable scalable, ultralow-power spintronic, neuromorphic and sensing devices. Here we report room-temperature ME coupling in transition-metal-doped Hf_0.3Zr_0.7O₂ (HZO) thin films. Structural analyses confirm a chemically homogeneous HZO matrix in which distinct polymorphs coexist, with uniform incorporation of the transition metal ions. The resulting films exhibit concurrently ferroelectricity and magnetism at room temperature, yielding a substantial magnetoelectric coupling, as corroborated by both macroscopic electrical measurements and microscopic piezoresponse force microscopy. This coupling is highly anisotropic, showing a positive response to in-plane magnetic fields and a weak negative response to out-of-plane fields, which can be explained by an interplay between positive magnetostriction and the unique negative piezoelectric coefficient of HZO. Our work establishes transition metal-doped HZO as a promising platform for single-material magnetoelectricity and opens a pathway for integrating multifunctional ME elements into silicon-compatible technologies.