Magnetoelastic thin films and multilayers for high-frequency applications

Magnetoelastic and magnetic high-frequency proper-ties of single and multilayer thin films are investigated with respect to applications in micro-inductors and as remote-interrogated sensors for mechanical quantities. The basic structure is a thin film inductor incorporating a magnetic material in order to enhance the inductance. In case of a sensor the inverse magnetostriction is used to change the permeability of the magnetic material and thus the inductance of the device. Materials properties like saturation magnetization, anisotropy field, resulting domain structures, electrical resistivity as well as the stress state of the films have to be adjusted carefully in order to meet certain requirements like high cut-off frequencies combined with low losses, and a high and controllable inverse magnetostrictive effect. In this paper (Fe-Co/Fe-Co-B-Si) multilayers are investigated in terms of their magnetic, high-frequency, and structural properties. (Fe50Co50/Co80B20) multilayers, e.g., have been fabricated which show ferromagnetic resonance frequencies up to 5 GHz while exhibiting a high inverse magnetostrictive effect up to the GHz frequency range. The obtained results for first LC circuits realized using (FC50Co50/Co80B20) multilayers are discussed.