Abstract
We study the magnetic behavior of thin films with thicknesses between and . The films are epitaxially grown on single crystals by atomic-oxygen-assisted molecular beam epitaxy. The thin films exhibit high structural order with sharp interfaces and low roughness and exhibit a Verwey transition for thicknesses above . However, the samples have magnetic properties that deviate from the bulk ones. The magnetic moment varies between for -thick film and for -thick film in a field of , which is lower than that of bulk samples ( formula). Still the magnetic saturation is never reached, even in fields as large as . The thinner the film, the slower the approach to saturation. Structural analysis, performed using high-resolution transmission electron microscopy, reveals the presence of antiphase boundaries (APB’s), the density of which decreases when the thickness increases. Using a model of ferromagnetic domains separated by antiferromagnetically sharp interfaces, we show that the slow approach to saturation observed in the films as a function of thickness is driven by the APB density.
- Received 15 April 2004
DOI:https://doi.org/10.1103/PhysRevB.70.174448
©2004 American Physical Society