Magnetic Trampoline Resonators Made of (La,Sr)MnO<sub>3</sub> Single-Crystal Thin Films.

Abstract

Microelectro-mechanical resonators employing a magnetic element have been proposed for magnetic field sensing applications, but the integration of magnetic materials with standard semiconductor compounds is challenging and requires complex fabrication protocols. We present a different approach relying on (La_0.7,Sr_0.3)MnO₃ (LSMO), an oxide compound that works both as a structural element for the resonator and a functional magnetic layer. Suspended trampolines are realized in a single-step process from LSMO thin films and show a quality factor of up to 60k and <i>f</i>·<i>Q</i> products reaching 10¹⁰ Hz. Their magnetic properties are probed by a SQUID magnetometer and magnetic force microscopy, showing a saturation magnetization of 240 kA/m at room temperature and in-plane magnetic domains with a coercivity of 2.5 mT. Being entirely made from a magnetic material, these resonators exhibit a larger magnetic interaction volume compared to other solutions, making them ideal candidates as building blocks for high-sensitivity magnetic field sensors.