Temperature-Dependent exchange bias of sputter deposited Fe3O4 thin films

Abstract

The structural and the temperature-dependent exchange bias properties of room temperature reactive sputtered Fe3O4 (150 nm) thin films are studied. The structural study shows that the films are polycrystalline with no preferred orientation. The exchange bias measurement performed at various temperatures shows a consistent increase in the magnitude of exchange bias field (HEB) as the temperature is lowered from 300 K, and showing a significant increase at low temperatures, which reaches a value of HEB = 190 Oe at 2 K. The presence of exchange bias effect is mainly due to the existence of a non-negligible exchange coupling between the core spins and the surface spins of Fe3O4 grains.