Multiferroicity in plastically deformed SrTiO$_3$

TL;DR

This paper demonstrates that plastic deformation induces robust, switchable magnetism and polar order in SrTiO3, establishing it as a quantum multiferroic and showcasing deformation as a tool for quantum materials engineering.

Contribution

It reveals that plastic deformation can create multiferroic properties in SrTiO3, a novel approach for quantum materials design.

Findings

Magnetism is localized along dislocation walls.

Magnetic order coexists with polar order.

Magnetism can be switched with external stress.

Abstract

A major challenge in the development of quantum technologies is to induce additional types of ferroic orders into materials that exhibit other useful quantum properties. Various techniques have been applied to this end, such as elastically straining, doping, or interfacing a compound with other materials. Plastic deformation introduces permanent topological defects and large local strains into a material, which can give rise to qualitatively new functionality. Here we show via local magnetic imaging that plastic deformation induces robust magnetism in the quantum paraelectric SrTiO3, in both conducting and insulating samples. Our analysis indicates that the magnetic order is localized along dislocation walls and coexists with polar order along the walls. The magnetic signals can be switched on and off in a controllable manner with external stress, which demonstrates that plastically deformed SrTiO3 is a quantum multiferroic. These results establish plastic deformation as a versatile platform for quantum materials engineering.