Polar octahedral rotations: a path to new multifunctional materials

TL;DR

This paper discusses how octahedral rotations in perovskite oxides can induce new ferroelectric properties and influence various physical phenomena, opening pathways for designing multifunctional materials.

Contribution

It introduces the concept of functional octahedral rotations and explores their potential to create novel properties in perovskite-based materials.

Findings

Octahedral rotations can induce hybrid improper ferroelectricity.

Rotations influence magnetic, orbital, and electronic properties.

Potential for electric field control of emergent phenomena.

Abstract

Perovskite ABO$_3$ oxides display an amazing variety of phenomena that can be altered by subtle changes in the chemistry and internal structure, making them a favorite class of materials to explore the rational design of novel properties. Here we highlight a recent advance in which rotations of the BO$_6$ octahedra give rise to a novel form of ferroelectricity -- hybrid improper ferroelectricity. Octahedral rotations also strongly influence other structural, magnetic, orbital, and electronic degrees of freedom in perovskites and related materials. Octahedral rotation-driven ferroelectricity consequently has the potential to robustly control emergent phenomena with an applied electric field. The concept of `functional' octahedral rotations is introduced and the challenges for materials chemistry and the possibilities for new rotation-driven phenomena in multifunctional materials are explored.