Tailoring the magnetomechanical power efficiency of metallic glasses for magneto-electric devices

Abstract

Metallic glasses with high magnetomechanical power efficiency are widely used in laminated magneto-electric devices, from passive magnetometers and solid-state converters to very-low-frequency emitters. The remaining challenge is to simultaneously enhance the magnetomechanical power coupling and quality factors that are usually counterbalanced in metallic glasses. Here, we investigate the relaxations and surface configurations in annealed metallic glasses and their impacts on the magnetomechanical properties. We found an opportune annealing condition that maximizes the power efficiency when a surface-oxidation film of boron oxide is formed with excessive boron atoms that are separated from a surface-crystalline film. We confirm the findings by demonstrating a magneto-electric gyrator that has a power efficiency of 96% and magneto-electric antennas that have an increased emission intensity by 20% than that with traditionally annealed metallic glasses.