Substrate effects on in-plane magnetic anisotropy and verwey transition temperatures of (100) magnetite (Fe₃O₄) films

(100) Fe₃O₄ films were grown on five different (100)-oriented substrates: MgO, MgAl₂O₄ (MAO), (PbMg_0.33Nb_0.67)_1-x:(PbTiO₃)_x (PMNT), SrTiO₃ (STO), and (LaAlO₃)_0.3(Sr₂AlTaO₆)_0.7 (LSAT), to investigate the substrate effects on structural, magnetic, and transport properties of the films. The X-ray diffraction measurements suggested that the epitaxial (100) Fe₃O₄ films were grown, although the lattice mismatch between the Fe₃O₄ and the substrates varied from +0.25% to -7.8%. Remarkably, the (100) Fe₃O₄ films grown on MAO, PMNT, and STO substrates exhibited a distinctive in-plane magnetic anisotropy with the magnetic easy axis along the [010] and [001] directions. In contrast, the (100) Fe₃O₄ films on the MgO and LSAT substrates showed a very weak anisotropy in the [011] easy direction. The Verwey transition temperature of the (100) Fe₃O₄ film was found to have a minimum value of ∼ 110K for MgO and a maximum value of ∼ 122K for STO. These results suggest that the magnetic anisotropy and Verwey transition behaviors of the (100) Fe₃O₄ film can be tuned by film growth on a specific substrate.