Magnetic Field Sensing by Exploiting Giant Nonstrain-Mediated Magnetodielectric Response in Epitaxial Composites

Heteroepitaxial magnetoelectric (ME) composites are promising for the development of a new generation of multifunctional devices, such as sensors, tunable electronics, and energy harvesters. However, challenge remains in realizing practical epitaxial composite materials, mainly due to the interfacial lattice misfit strain between magnetostrictive and piezoelectric phases and strong substrate clamping that reduces the strain-mediated ME coupling. Here, we demonstrate a nonstrain-mediated ME coupling in PbZr_0.52Ti_0.48O₃ (PZT)/La_0.67Sr_0.33MnO₃ (LSMO) heteroepitaxial composites that resolves these challenges, thereby, providing a giant magnetodielectric (MD) response of ∼27% at 310 K. The factors driving the magnitude of the MD response were found to be the magnetoresistance-coupled dielectric dispersion and piezoelectric strain-mediated modulation of magnetic moment. Building upon this giant MD response, we demonstrate a magnetic field sensor architecture exhibiting a high sensitivity of 54.7 pF/T and desirable linearity with respect to the applied external magnetic field. The demonstrated technique provides a new mechanism for detecting magnetic fields based upon the MD effect.