Work

Turning point identification via exploring the thickness dependence of magnetoresistance in polycrystalline Fe3O4 thin films

Year: 2025

Type: article

Abstract: Stoichiometric polycrystalline Fe3O4 films with thicknesses ranging from 25 to 165 nm were fabricated on Si (100) substrates with a native SiO2 layer via pulsed laser deposition, followed by vacuum annealing at 780 °C. Negative magnetoresistance was observed, and the absolute magnetoresistance under an applied magnetic field of 0.9 T (|MR|0.9 T) was systematically investigated. In contrast to previous studies, the maximum |MR|0.9 T of 2.68% was achieved at a thickness of 50 nm. Films with thicknesses in the range of 40–88 nm retained relatively high |MR|0.9 T values. However, when the thickness increased to 100 nm, |MR|0.9 T dropped sharply to 1.70% and then decreased gradually with further increases in thickness. Raman characterization and magnetoresistance curve fitting revealed that the largest |MR|0.9 T value corresponded to the lowest density of antiphase boundaries. Additionally, the Verwey transition temperature (TV) derived from temperature-dependent resistance curves was closest to that of bulk Fe3O4 when the film thickness was in the range of 45–55 nm.

Source: Journal of Applied Physics

DOI: 10.1063/5.0293279