Thermoelectric Power in the Double Exchange Model

TL;DR

This study investigates the temperature-dependent thermoelectric power in the double exchange model using Monte Carlo and exact diagonalization, revealing distinct behaviors across temperature regimes and effects of magnetic fields.

Contribution

It provides new insights into the temperature dependence of thermoelectric power in the double exchange model, especially near magnetic transition temperatures and under magnetic fields.

Findings

TEP follows Heikes formula at high temperatures.

TEP is suppressed by exchange coupling at intermediate temperatures.

Anomalous peak and dip in TEP near magnetic transition temperature.

Abstract

Employing the Monte-Carlo method and the exact diagonalization, we have investigated the temperature dependence of the thermoelectric power (TEP) for the double exchange model in the dilute carrier concentration limit. We have found that the TEP follows the Heikes formula in the high temperature regime, whereas, in the intermediate temperature regime, the TEP is suppressed by the exchange coupling between itinerant electrons and local spins. In the low temperature regime, the TEP exhibits an anomalous peak and dip feature near the magnetic transition temperature $T_C$ which can be understood based on the magnetic polaron state. We have also found that the TEP, in the presence of the magnetic field, shows the positive magnetothermoelectric power near $T_C$.