Novel Functionality in Switchable Polar Materials

Abstract

In research on functional materials, the focus of attention has increasingly shifted from ferroelectrics, with electric‐field‐driven switching between two or more symmetry‐related insulating polar states, to materials with functional behavior based on the competition of antipolar and polar states, or two or more symmetry inequivalent polar states, with switching driven by applied electric fields and/or stresses. When the competing states are not symmetry related, they can have quite distinct magnetic, optical, transport, and topological properties, with functionality derived from modulating these properties or even turning them on and off. In this perspective, the authors set out joint experimental–theoretical strategies for the discovery and development of new functional materials in this class.

Halide perovskites from first principles: from fundamental optoelectronic properties to the impact of structural and chemical heterogeneity

“…They consist of anionic metal-halide octahedra connected through their corners in three, two, one or zero dimensions and charge-compensated by inorganic or organic cations. Contrary to the structurally related oxide perovskites that have been studied intensely for decades for their ferroelectric, superconducting, magnetic, multiferroic, and other emerging properties [19][20][21], halide perovskites only recently received a surge of interest, primarily because of the outstanding photovoltaic efficiency of the organic-inorganic halide perovskite CH 3 NH 3 PbI 3 . In the following, we give an overview of the most important perovskite (-inspired) material classes covered in this review, diverging from a strict definition of ABX 3 perovskites.…”