Spiral Annealing of Magnetic Microwires

A preprocessing technique named “spiral annealing” was applied for the first time to
magnetic microwires. In this process, the sample was arranged in a flat spiral shape during annealing,
and subsequent measurements were conducted on the unbent sample with the induced stress
distribution along and transverse to the sample. The research utilized both magnetic and magnetooptical
methods. The anisotropy field magnitude in both the volume and surface of the microwire was
measured, and for the first time, a direct correlation between the anisotropy field and the curvature
of a spirally annealed microwire was established. Additionally, a connection between the type of
surface domain structure and the degree of spiral curvature was identified. The preservation of the
distribution of spiral annealing-induced magnetic properties both along and across the microwire is a
key effect influencing the technological application of the microwire. The range of induced curvature
within which a specific helical magnetic structure can exist was also determined. This insight links the
conditions of spiral annealing to the selection of microwires as active elements in magnetic sensors.