Core/shell bimagnetic microwires with asymmetric shell: MOKE and FMR behavior

Abstract

A new type of multilayered microwires with a partially covering shell and bimagnetic character is here introduced. A precursor Pyrex-coated Fe-based microwire was fabricated by quenching and drawing technique, and subsequently an outer magnetic shell was deposited by magnetron sputtering covering only partly the precursor microwire (contrary to previously reported fully covered wires). Particularly, an amorphous magnetically soft core (Fe77.5B15Si7.5) was selected in this study and a polycrystalline shell (FeNi soft or Co hard) covered only half of microwire along the axis. After performing a geometry and surface roughness characterization, their surface azimuthal static magnetic profile was determined by magneto-optic Kerr-magnetometer, MOKE. In addition, the ferromagnetic resonance, FMR, response was experimentally studied by Network Analyzer up to 16 GHz frequency where the contributions of internal core and partly covering shell are analyzed and compared with fully covered microwires. The magnetoelastic behavior of such asymmetric bimagnetic microwires open up new perspectives to employ such materials for sensing and biomedical tweezer applications.