Ferroic properties and piezoelectric response of Mg2XN3 (X = V, Cr)

Abstract

Nitrides are of increasing interest since they are usually wide-bandgap semiconductors and the available environmental raw materials are abundant. Using first-principles predictions, we reveal that Mg2XN3 (X = V, Cr) compounds show remarkably large ferroelectric polarization and piezoelectric response. Quantitative theoretical analysis further indicates the asymmetric orbital hybridization to be the origin of the ferroelectricity. Since Cr has one more 3d electron than V, it is found that Mg2CrN3 is multiferroic with a ferromagnetic ground state. We further show that the epitaxial strain can regulate the piezoelectricity, and thus, both Mg2CrN3 and Mg2VN3 exhibit a larger piezoelectric response than the reported nitride piezoelectric materials under appropriate tensile epitaxial strain. Our findings provide guidance for potential applications of nitride materials in spintronics, sensors, and memory devices.