Robust Anomalous Hall Effect in Epitaxial Cubic D03-Fe3Ge Nanoplates Grown via Chemical Vapor Deposition

Abstract

Iron-based ferromagnetic materials have emerged as a promising system for spintronics due to their high Curie temperatures and the significant anomalous Hall effect (AHE) driven by Berry curvature. While there have been investigations into the epitaxial growth of nonlayered iron-based ferromagnetic materials, the realization of high-quality single crystal thin films continues to be a formidable obstacle. Meanwhile, issues such as grain boundary scattering further hinder their characterization and application. Here, we report the first chemical vapor deposition synthesis of single-crystalline cubic D03-Fe3Ge nanoplates. This compound represents a substantial departure from the conventional hexagonal phases typically observed in the Fe–Ge system. Structural characterizations confirm the cubic lattice and the stoichiometric purity of the crystals. Structural analysis identifies a strong epitaxial effect, resulting in a giant compressive strain of ∼4.16% at the interface that relaxes gradually toward the surface. The second-harmonic generation signals might further reveal that such interfacial strain disrupted the inherent centrosymmetry of the cubic phase. Superconducting quantum interference device magnetometry shows robust room-temperature ferromagnetism and clear magnetic anisotropy. Magneto-transport measurements reveal a robust AHE that remains stable at temperatures far exceeding the room temperature. The scaling observed between the anomalous Hall resistance and longitudinal resistance strongly suggests that this effect is dominated by the intrinsic Berry curvature mechanism. Furthermore, density functional theory calculations reveal that the huge epitaxial strain induces band reconstructions and creates dense spin–orbit coupling gaps near the Fermi level, effectively doubling the anomalous Hall conductivity to match our experimental observations.