# Strong Electron-Phonon Interaction and Colossal Magnetoresistance in EuTiO$_3$

## TL;DR

This paper investigates the origin of colossal magnetoresistance in EuTiO₃, attributing it to electron-phonon interactions forming a tiny conduction subband near the Fermi level, which is sensitive to magnetic shifts.

## Contribution

It combines first-principles calculations and dynamical mean-field theory to explain the large resistivity and magnetoresistance in EuTiO₃ due to electron-phonon interactions and magnetic effects.

## Key findings

- Electron-phonon interaction creates a tiny subband near the Fermi level.
- Magnetization shifts the subband, causing colossal magnetoresistance.
- EuTiO₃ exhibits large resistivity at low temperatures.

## Abstract

At low temperatures, EuTiO$_3$ system has very large resistivities and exhibits colossal magnetoresistance. Based on a first principle calculation and the dynamical mean-field theory for small polaron we have calculated the transport properties of EuTiO$_3$. It is found that due to electron-phonon interaction the conduction band may form a tiny subband which is close to the Fermi level. The tiny subband is responsible for the large resistivity. Besides, EuTiO$_3$ is a weak antiferromagnetic material and its magnetization would slightly shift the subband via exchange interaction between conduction electrons and magnetic atoms. Since the subband is close to the Fermi level, a slight shift of its position gives colossal magnetoresistance.