Crossover of uniaxial magnetic anisotropy direction mediated by interfacial strain of CoFe2O4 films

This study examined the deposition temperature dependent magnetic anisotropy of CoFe2O4 films grown on Al2O3(0001) substrates using pulsed-laser deposition. X-ray diffraction revealed all films to have a < 111 > orientation except for the films grown at room temperature, which exhibited amorphous characteristics. Furthermore, the films deposited between 350 degrees C and 550 degrees C exhibited out-of-plane tensile strain even though, which was relieved as the deposition temperature increased. On the other hand, film deposited at 650 degrees C showed out-of-plane compressive strain. The in-plane and out-of-plane magnetic hysteresis loops, which were measured at room temperature, showed a decreased out-of-plane anisotropy when the deposition temperature was increased. Simple uniaxial magnetic anisotropy energy calculations based on the experimental data showed a direct correlation between the uniaxial magnetic anisotropy direction and stress of the films. X-ray photoelectron spectroscopy revealed variations in the cation distribution according to the deposition temperature. (C) 2014 Elsevier B.V. All rights reserved.