Tunable domain wall dynamics in amorphous ferromagnetic microwires

Abstract

Abstract In this work, we show the possibility of tuning the domain wall dynamics in amorphous ferromagnetic microwires by means of thermal annealing. We investigate the effect of annealing time and temperature on the field dependence of the domain wall velocity in magnetically bistable Fe- and CoFeNi-based microwires. We demonstrate that the magnitude of the magnetostriction coefficient determines the tendency of the domain wall mobility and velocity change and we relate the magnetostriction coefficient to the stress relaxation upon annealing. Thus, in the case of Fe-based microwires with large positive magnetostriction ∼10−6 the stress relaxation caused by the annealing leads to an increase of the velocity and mobility of the domain wall, while the same parameters of the domain wall dynamics for CoFeNi-based microwires with nearly zero magnetostriction coefficient ∼10−7-10−8 significantly decrease. Growth of the minimum magnetic field for domain wall propagation upon annealing is observed in CoFeNi microwires with vanishing magnetostriction coefficient. This influence of annealing on the domain wall dynamics of CoFeNi microwires is explained by considering domain wall stabilization due to pair ordering. The opposite tendency observed for Fe-based microwires with only one transition metal is associated with the stress relaxation upon annealing.