Novel Functionality in Switchable Polar Materials from First Principles

This proposal describes a first-principles approach to the investigation of the mechanisms for functional behavior in oxides, chalcogenides and intermetallic compounds, with a focus on the design and discovery of materials with functional behavior driven by applied electric fields and stress. Systems of particular interest are piezoelectrics, ferroelectrics, antiferroelectrics, andmaterials with electric-field- or stress-controlled magnetic, optical, transport and topological properties. The planned projects include (1) identification of new functional materials characterized by symmetry-inequivalent competing low-energy states, including antiferroelectrics, double ferroelectrics, and fraternal-twin ferroelectrics; (2) identification of new piezoelectric materials and mechanisms starting with a high-throughput search of the Berkeley ferroelectric database; (3) investigation of the rich physics of ferroelectrics with freecarriers, including leaky ferroelectrics, doped ferroelectrics, and electric-field-switchable polar metals; (4) analysis and modeling of functional behavior mediated by nonpolar instabilities, including improper ferroelectricity, enhanced piezoelectricity, and piezochromic and piezoconductive responses; and (5) modeling of polarization switching in applied electric fields, including high-throughput use of the Berry flux diagonalization method. Interaction withexperimental groups will be enhanced by the continued development of virtual instrument tools that connect first-principles results to experimental measurements.