Some magnetic properties of Mn-Zn ferrite epitaxial layers

Abstract

Mn-Zn spinel ferrite films grown by liquid phase epitaxy on MnGa 2O4 substrates in controlled atmospheres have been studied. We have characterized films whose composition ranged from Mn .9Zn.5Fe1.6O4 for saturation magnetization, induced anisotropy, Curie temperature and in-plane coercivity. The ferromagnetic (FMR) and spin wave resonance spectra show the correlation of film magnetization, induced anisotropy and homogeneity with composition. Two magnetic phases are evident from the FMR spectra and hysteresis for films with a composition near Mn.9Zn.5Fe1.6O4. The second phase is not present in films with more than 1.7 Fe atoms/formula unit. The variation of the FMR linewidth with temperature is attributed to the presence of either Mn3+ or Fe2+. A large stress correlated (but not simply magnetostrictive) uniaxial anisotropy is apparent. Using a vibrating sample magnetometer film moments have been measured from room temperature through their Curie points. An in-plane coercivity of less than 3 Oe has been observed in a good quality film of composition near Mn .3Zn.2Fe2.5O4 and having a film/substrate lattice mismatch of approximately -0.002 Å (film in compression).