Verwey transition in Fe${}_3$O${}_4$ thin films: Influence of oxygen stoichiometry and substrate-induced microstructure

Abstract

We have carried out a systematic experimental investigation to address the question why thin films of Fe${}_3$O${}_4$ (magnetite) generally have a very broad Verwey transition with lower transition temperatures as compared to the bulk. We observed using x-ray photoelectron spectroscopy, x-ray diffraction and resistivity measurements that the Verwey transition in thin films is drastically influenced not only by the oxygen stoichiometry but especially also by the substrate-induced microstructure. In particular, we found (1) that the transition temperature, the resistivity jump, and the conductivity gap of fully stoichiometric films greatly depends on the domain size, which increases gradually with increasing film thickness, (2) that the broadness of the transition scales with the width of the domain size distribution, and (3) that the hysteresis width is affected strongly by the presence of antiphase boundaries. Films grown on MgO (001) substrates showed the highest and sharpest transitions, with a 200 nm film having a T${}_V$ of 122K, which is close to the bulk value. Films grown on substrates with large lattice constant mismatch revealed very broad transitions, and yet, all films show a transition with a hysteresis behavior, indicating that the transition is still first order rather than higher order.

arXiv comment9 pages, 12 figures

References in corpus (4)

• Extrinsic Magnetotransport Phenomena in Ferromagnetic Oxides
• Non-volatile ferroelastic switching of the Verwey transition and resistivity of epitaxial Fe3O4/PMN-PT (011)
• Converse Magnetoelectric Effects in Fe3O4/BaTiO3 Multiferroic Hybrids
• Field-dependent anisotropic magnetoresistance and planar Hall effect in epitaxial magnetite thin films

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• Facet-dependent magnon-polarons in epitaxial ferrimagnetic Fe3O4 thin films
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• Interfacing topological insulators and ferrimagnets: Bi${}_2$Te${}_3$ and Fe${}_3$O${}_4$ heterostructures grown by molecular beam epitaxy
• Structural peculiarities of $\epsilon$-Fe${}_2$O${}_3$ / GaN epitaxial layers unveiled by high-resolution transmission electron microscopy and neutron reflectometry
• UCd${}_{11}$: A strongly localized 5$f^3$ material
• Towards magnetic control of magnetite