Spin-polaron model: transport properties of EuB$_6$

TL;DR

This paper models the transport properties of EuB$_6$ using a spin-polaron Hamiltonian that includes electron-phonon interactions, successfully explaining temperature and magnetic field effects on resistivity and magnetoresistance.

Contribution

It introduces a comprehensive spin-polaron model incorporating electron-phonon interactions to explain EuB$_6$'s transport phenomena, including magnetoresistance and temperature dependence.

Findings

Resistivity's temperature and magnetic field dependence are well explained.

Magnons dominate conduction at low temperatures.

Lattice scattering becomes significant at high temperatures.

Abstract

To understand anomalous transport properties of EuB$_6$, we have studied the spin-polaron Hamiltonian incorporating the electron-phonon interaction. Assuming a strong exchange interaction between the carriers and the localized spins, the electrical conductivity is calculated. The temperature and magnetic field dependence of the resistivity of EuB$_6$ are well explained. At low temperature, magnons dominate the conduction process, whereas the lattice contribution becomes significant at very high temperature due to the scattering with the phonons. Large negative magnetoresistance near the ferromagnetic transition is also reproduced as observed in EuB$_6$.