A Model of the Normal State Susceptibility and Transport Properties of Ba(Fe1-xCox)2As2: Why does the magnetic susceptibility increase with temperature?

TL;DR

This paper presents a simple two-band model that explains the temperature-dependent magnetic susceptibility and transport properties of Ba(Fe1-xCox)2As2, revealing why susceptibility increases with temperature.

Contribution

It introduces a minimal three-parameter two-band model that semi-quantitatively reproduces magnetic and transport data, including the susceptibility increase, for FeAs-based semimetals.

Findings

Model reproduces susceptibility and transport trends

Explains the increase of magnetic susceptibility with temperature

Provides insights into electronic structure of FeAs materials

Abstract

A simple two-band model is used to describe the magnitude and temperature dependence of the magnetic susceptibility, Hall coefficient and Seebeck data from undoped and Co doped BaFe2As2. Overlapping, rigid parabolic electron and hole bands are considered as a model of the electronic structure of the FeAs-based semimetals. The model has only three parameters: the electron and hole effective masses and the position of the valence band maximum with respect to the conduction band minimum. The model is able to reproduce in a semiquantitative fashion the magnitude and temperature dependence of many of the normal state magnetic and transport data from the FeAs-type materials, including the ubiquitous increase in the magnetic susceptibility with increasing temperature.