Design of multilayer microwires with controllable magnetic properties: Magnetostatic and magnetoelastic coupling

Novel two-magnetic-phase multilayer microwires with outstanding controllable behaviour are introduced. They are obtained by suitable combined processing techniques, such as the quenching and drawing method, sputtering and/or electroplating, and consist of a magnetic nucleus, intermediate non-magnetic layers and an outer magnetic layer. In this work, an ultrasoft CoFe-based amorphous nucleus and a magnetically harder crystalline CoNi outer layer are considered. The magnetostatic interaction between magnetic phases is proven to give rise to antiferromagnetic-like coupling, resulting in biasing of the magnetic behaviour of the soft nucleus. In addition, the effective magnetic anisotropy of the latter is tailored by the magnetoelastic coupling between the nucleus and the external layers through the stresses induced during the fabrication process and by their differential thermal expansion coefficients. This new family of microwires shows excellent magnetic properties which, being tailorable, make them ideal materials for novel or optimized elements in sensor devices.