Breaking Symmetry with Light: Ultra-Fast Ferroelectricity and Magnetism from Three-Phonon Coupling

TL;DR

This paper presents a theoretical framework for inducing transient ferroic properties like ferroelectricity and ferromagnetism using ultra-fast light pulses through three-phonon coupling, highlighting potential for rapid control of material states.

Contribution

It introduces a novel theory explaining how symmetry breaking via three-phonon interactions can produce transient ferroic states under ultra-fast excitation, with specific focus on degenerate phonon resonance conditions.

Findings

Resonant pumping of degenerate phonons can produce ultrafast ferroic responses.

The theory explains previous femto-magnetism experiments in different frequency ranges.

Candidate materials for light-induced ferroelectricity and ferromagnetism are proposed.

Abstract

A theory describing how ferroic properties can emerge transiently in the ultra-fast regime by breaking symmetry with light through three-phonon coupling is presented. Particular emphasis is placed on the special case when two exactly degenerate mid-infra-red or THz phonons are resonantly pumped, since this situation can give rise to an exactly rectified ferroic response with damping envelopes of ~ 1 ps or less. Light-induced ferroelectricity and ferromagnetism are discussed in this context, and a number of candidate materials that could display these phenomena are proposed. The same analysis is also applied to the interpretation of previous femto-magnetism experiments, performed in different frequency ranges (visible and near-infrared), but sharing similar symmetry characteristics.