High-frequency magnetoelastic multilayer thin films and applications

This paper gives an overview of recent advances in applying magnetoelastic thin films in inductive high-frequency devices. Single and multilayer films were fabricated and optimized with respect to application in stress-sensitive inductors, which are operated at high frequencies. These films require high magnetic permeability, high ferromagnetic resonance frequency, low losses, and a high inverse magnetostrictive effect. A thin-film LC circuit with incorporated magnetic thin films, sensitive to applied external magnetic field and/or applied stress, is presented. It operates at a frequency of about 0.5 GHz and has a quality factor of 8, allowing wireless interrogation, e.g., by inductive coupling. Applied strain in a range <0.1% leads to a change of resonance frequency of up to 20%.