Multi-jump magnetization switching in Co2FeAl full Heusler alloy thin films: Experiments and simulations

Co2FeAl (CFA) thin films of 50 nm thickness have been grown on MgO (001) single crystal substrates at room temperature with and without post-annealing (PA) at 300 degrees C and 400 degrees C using dual ion-beam sputtering technique. The XRD pattern of the as-grown film revealed that CFA grows with preferred crystallographic orientation on the MgO (001) substrate. Temperature dependent anisotropy measurements on PA films revealed a dominating contribution from cubic anisotropy as confirmed by the analysis of azimuthal angle dependent longitudinal in-plane magneto-optical Kerr effect (MOKE) measurements. The contributions from the cubic and uniaxial anisotropies have also been quantified employing ferromagnetic resonance spectroscopy. Magnetization reversal is accompanied with a plateau in the MOKE hysteresis recorded at various azimuthal angles in the in-plane applied magnetic field configuration. The occurrence of the observed plateau is explained by the presence of a combination of domain walls such as 90 degrees, 135 degrees and 180 degrees domain walls and/or complex domains which is supported by results from micromagnetic simulations. These results demonstrate the feasibility of manipulating the magnetization switching in one of the two ferromagnetic electrodes of the magnetic tunnel junction devices based on Heusler alloy ferromagnetic films.