Cylindrical magnetization model for glass-coated microwires with circumferential anisotropy: Comparison with experiments and skin effect

• We model magnetic properties of microwires with circumferential anisotropy.
• Skin effect correction has to be considered for small microwires.
• Validity of model is proved by permeability dependence on axial static field.
• Wires with small volume of the core can be well described by macrospin approach.
• The exchange-coupled continuous core-shell model is compared to experiments.

The present manuscript represents the third part of a series of studies about a continuous micromagnetic model for amorphous microwires with non-uniform magnetic structure (Torrejon et al., J. Magn. Magn. Mater. 323 (2011) 283; Torrejon et al., J. Magn. Magn. Mater. 333 (2013) 144). Here we compare the predictions of this model with experiments, and show the validity of this approach when a uniform magnetic structure in the microwire cannot be considered. The analyzed microwires exhibit ultrasoft magnetic behaviour and negative magnetostriction, with a non-uniform magnetic structure composed of an axially magnetized inner core exchange-coupled with a circumferentially magnetized outer shell. The static properties were obtained by magnetometry. The high frequency response, axial permeability, was measured from a conventional single coil permeameter connected to a network analyzer. The microwave response is strongly affected by skin effect, which therefore needs to be taken into account for comparison with theory. The validity of the continuous model is proved through the experimental dependence of the permeability on axial static field. Finally, the efficient dynamic magnetization is evaluated from the imaginary component of permeability.