Toward mechano-spintronics: Nanostructured magnetic multilayers for the realization of microcantilever sensors featuring wireless actuation for liquid environments

Abstract

Silicon microcantilevers are realized and tested using different ferromagnetic thin films as active actuators. The exploited design is optimized for operating the sensor in a liquid environment. Different magnetic materials are used as actuator elements: a soft layer of face-centered cubic Co, a hard layer of Co₈₀Cr₂₀ (subscript: atomic composition in percentage) and a (Co⁵Cu¹⁰)₅ multilayer (superscript: thickness; subscript: number of repetitions). The thin film magnetizations are characterized both in the film plane and out of it. We characterize the devices in air and in water comparing piezoelectric and magnetic actuation, confirming that nanostructured magnetic multilayers represent a new and promising route to optimize the actuation of magnetic microcantilevers. Complete sets of dynamical measures, consisting of stability plots, are discussed. Finite element simulations performed with a commercial code and inherent to a static analysis of different magnetic microcantilevers are commented, casting more light on the importance of having a nanostructured actuator for a high-efficiency energy transfer. This opens the route to new challenging devices, where the spin arrangement at the nanoscale is used to induce either mechanical deformations or movements by effect of an electromagnetic field.