Giant electro-thermal conductivity and spin-phonon coupling in an antiferromagnetic oxide

TL;DR

This study reveals that weak electric fields significantly enhance thermal conductivity in an antiferromagnetic oxide by suppressing phonon scattering through charge-spin interactions, enabling reversible control of spin fluctuations.

Contribution

It demonstrates a novel electro-thermal effect in CaMnO3, linking electric field-induced charge mobility with spin-phonon coupling and thermal transport.

Findings

Weak electric fields increase thermal conductivity near Neel temperature.

Charge de-trapping reduces phonon scattering in the material.

Reversible control of spin fluctuations via external electric fields.

Abstract

The application of weak electric fields (<~ 100 V/cm) is found to dramatically enhance the lattice thermal conductivity of the antiferromagnetic (AF) insulator CaMnO(3) over a broad range of temperature about the Neel ordering point (125 K). The effect is coincident with field-induced de-trapping of bound electrons, suggesting that phonon scattering associated with short- and long-ranged AF order is suppressed in the presence of the mobilized charge. This interplay between bound charge and spin-phonon coupling might allow for the reversible control of spin fluctuations using weak external fields.