Substrate Effects on In-Plane Magnetic Anisotropy and Verwey Transition Temperatures of (100) Magnetite (Fe3O4) Films

(100) Fe 3 O 4 films were grown on five different (100)-oriented substrates: MgO, MgAl 2 O 4 (MAO), (PbMg 0.33 Nb 0.67 ) 1-x :(PbTiO 3 ) x (PMNT), SrTiO 3 (STO), and (LaAlO 3 ) 0.3 (Sr 2 AlTaO 6 ) 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) Fe 3 O 4 films were grown, although the lattice mismatch between the Fe 3 O 4 and the substrates varied from +0.25% to -7.8%. Remarkably, the (100) Fe 3 O 4 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) Fe 3 O 4 film was found to have a minimum value of ~110 K for MgO and a maximum value of ~122 K for STO. These results suggest that the magnetic anisotropy and Verwey transition behaviors of the (100) Fe 3 O 4 film can be tuned by film growth on a specific substrate.