Magnetization reversal in thin glass covered amorphous microwires with helical anisotropy

The surface magnetization reversal has been studied in Co-rich amorphous glass-covered microwires. The studies have been performed by the magneto-optical Kerr effect surface loop tracer for the series of the microwires with diameters of 16.8-5.8 μm. The experiments have been carried out in the crossed axial and circular magnetic fields. The variety of the magnetic behaviour has been found in dependence on the diameter of the microwire, that confirms the existence of the helical domain structure in the Co-rich microwires. The special behaviour has been discovered for the wire with the diameter of 10 μm. From this results we can conclude that the axially magnetized inner core disappears for this value of the microwire diameter and that the domain structure of the microwire consists only of the helical domain structure. The experiments are in good agreement with calculations based on the model taking into account the existence of the helical anisotropy in the surface area of the microwires.