Spiral annealing influence on magnetic structure in magnetic microwires

Glass-covered microwires were studied after spiral annealing. Before annealing, the sample was laid out in the form of a geometric spiral with a given curvature. After annealing, the sample was straightened and analyzed. Using a magneto-optical technique, both new surface magnetic structures induced by spiral stress annealing and magnetization reversal processes were studied. Spiral stress annealing causes the formation of an internal stress gradient from tension to compression across the sample. This stress gradient smoothly changes along the length of the microwire. A gradual change in the anisotropy field with the length of the sample was observed on the surface of the microwire.

We highlight two main results depending on the longitudinal location of the observation: the effect of the transverse stress gradient on the motion of domain walls and the effect of the transverse stress gradient on the process of magnetic domain nucleation.