Giant Optical Polarization Rotation Induced by Spin-Orbit Coupling in Polarons

TL;DR

This paper reports a giant magneto-optical response in doped manganite caused by small polarons, revealing a new mechanism involving spin-orbit coupling that could enable advanced nonreciprocal optical devices.

Contribution

It uncovers a novel giant gyrotropic response driven by small polarons and spin-orbit coupling, challenging the traditional band structure perspective.

Findings

Giant gyrotropic magneto-optical response observed near transition temperature.

Small polarons identified as key to the phenomenon.

Interplay of mobility, Jahn-Teller effect, and spin-orbit coupling explained.

Abstract

We have uncovered a giant gyrotropic magneto-optical response for doped ferromagnetic manganite La2/3Ca1/3MnO3 around the near room-temperature paramagnetic-to-ferromagnetic transition. At odds with current wisdom, where this response is usually assumed to be fundamentally fixed by the electronic band structure, we point to the presence of small polarons as the driving force for this unexpected phenomenon. We explain the observed properties by the intricate interplay of mobility, Jahn-Teller effect and spin-orbit coupling of small polarons. As magnetic polarons are ubiquitously inherent to many strongly correlated systems, our results provide an original, general pathway towards the generation of gigantic gyrotropic responses that can be harnessed for nonreciprocal devices that exploit the polarization of light.