Thickness dependence of anomalous magnetic behavior in epitaxial Fe{sub 3}O{sub 4}(111) thin films: Effect of density of antiphase boundaries
- DSM/DRECAM/SPCSI, CEA Saclay, 91191 Gif-sur-Yvette (France)
We study the magnetic behavior of Fe{sub 3}O{sub 4}(111) thin films with thicknesses between 5 nm and 50 nm. The films are epitaxially grown on {alpha}-Al{sub 2}O{sub 3}(0001) single crystals by atomic-oxygen-assisted molecular beam epitaxy. The Fe{sub 3}O{sub 4}(111) thin films exhibit high structural order with sharp interfaces and low roughness and exhibit a Verwey transition for thicknesses above 8 nm. However, the samples have magnetic properties that deviate from the bulk ones. The magnetic moment varies between 2.4{mu}{sub B} for 5-nm-thick film and 3.2{mu}{sub B} for 50-nm-thick film in a field of 1.2 T, which is lower than that of bulk samples (4.1{mu}{sub B}/Fe{sub 3}O{sub 4} formula). Still the magnetic saturation is never reached, even in fields as large as 2 T. 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.
- OSTI ID:
- 20664951
- Journal Information:
- Physical Review. B, Condensed Matter and Materials Physics, Vol. 70, Issue 17; Other Information: DOI: 10.1103/PhysRevB.70.174448; (c) 2004 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA); ISSN 1098-0121
- Country of Publication:
- United States
- Language:
- English
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