Circular Magnetoelastic Anisotropy Induced in the Nucleus of an FeSiB-CoNi Soft-Hard Bi-Phase Microwire

Multilayer amorphous microwires have been prepared coating a precursor FeSiB amorphous nucleus with a crystalline CoNi outer layer. The FeSiB as-cast amorphous wire is characterised by an unique bistable behavior where magnetization reverses from one remanent state to another through a single large Barkhausen event at a field value known as switching field, H_sw. In multilayer microwires, the presence of a second magnetic phase, a magnetically harder CoNi layer, substantially modifies the values of H_sw via two coupling mechanisms: magnetoelastic and magnetostatic interactions between the two phases. In this paper, a systematic study on the effects of the geometrical characteristic of the outer phase on the H_sw behavior is presented. M-H analysis and fluctuation studies by induction technique were performed on a family of samples having different CoNi thicknesses.