The magnetotransport and magnetic properties of epitaxial ${\mathrm{Fe}}_3{\mathrm{O}}_4$ thin films grown on (001)-oriented MgO substrates by pulsed-laser deposition have been investigated. The magnetoresistance (MR) exhibits a peak around the Verwey transition ${(T}_{\nu })$ as has also been reported previously for single crystals. Additionally, we have observed that the MR increases monotonically below 100 K with decreasing temperature. MR values as high as 32% have been observed for a 6600-Å-thick film at 60 K under a 4-T field. The enhanced low-temperature MR is attributed to a magnetic-field-dependent activation energy for electron hopping transport.

• Received 27 March 1997

DOI:https://doi.org/10.1103/PhysRevB.56.5096