Structural, magnetic and magnetodielectric properties of the Mn3O4 thin films epitaxially grown on SrTiO3 (001) substrates

• Epitaxial Mn3O4 films with biaxial compressive in-plane strain have been fabricated on SrTiO3 surface.
• The film exhibits obvious magnetodielectric behavior near the paramagnetic–ferrimagnetic transition temperature.
• The magnetic and magnetodielectric properties are tuned by the in-plane strain.
• The strong coupling between lattice, spin, and orbital degrees of freedom in Mn3O4 is determined.

The (001)-orientated Mn3O4 thin films were fabricated on Nb-doped SrTiO3 (001) substrates by a pulsed laser deposition method, and the structural, magnetic, and magnetodielectric properties were investigated. We found that the as-prepared thin film is tetragonal with biaxial compressive strain in the film plane. The orientation relationship in the film plane is Mn3O4 [100] || SrTiO3 [110]. Compared with the single crystals, the paramagnetic–ferrimagnetic transition temperature TN is greatly increased due to the in-plane compressive strain. At TN, a sharp drop in the dielectric constant was observed. Under a magnetic field, the dielectric constant shows a negative field-direction dependent response around TN. Our experiments indicated the strong coupling between the strain, lattice, spin, and orbital degrees of freedom in the epitaxial Mn3O4 thin films.