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) Fe
₃
O
₄
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
$\sim 110$
K for MgO and a maximum value of
$\sim 122$
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.