Effect of temperature on the magnetic properties of Fe₃O₄ thin films studied by ferromagnetic resonance (FMR)

Abstract

Single crystalline Fe3O4 thin films of 110 Å thickness grown on MgO (100) substrate have been investigated by Ferromagnetic Resonance (FMR) technique as a function of temperature between 3 and 300 K. A strong unidirectional (exchange) anisotropy field was detected as evidence from a shift of the resonance field for the r‐FC case relative to that for n‐FC case at lower temperature. Using a field‐induced unidirectional exchange and bulk anisotropy, with the usual magneto‐crystalline cubic anisotropy energy, we have simulated both the experimental spectra and angular dependence of resonance field to deduce anisotropy and other magnetic parameters as a function of temperature. Magnetic parameters and Verwey transition for the thin film case were found to shift down to around 90 K from 120 K for bulk sample of the same compound as well. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)