Influence of Charge Density Waves on the Hall coefficient in NiTi

TL;DR

This study develops a mean-field charge density wave theory for NiTi, analyzing its impact on the Hall coefficient and related electronic properties, and compares theoretical predictions with experimental data.

Contribution

It introduces a charge density wave model that explains the Hall coefficient behavior in NiTi, highlighting the importance of biaxial charge density waves.

Findings

Biaxial charge density waves match experimental Hall coefficient data.

Uniaxial charge density waves do not reproduce the Hall coefficient accurately.

Hot spots dominated by Ni d-orbitals significantly influence the Hall effect.

Abstract

We present a mean-field charge density wave theory for NiTi using density functional theory bandstructure as a starting point. We calculate the Hall coefficient as a function of temperature and compare with recent experimental results. We analyze the contributions to the Hall coefficient from different parts of the Fermi surface and find that the Hall coefficient is dominated by certain ``hot spots''. The analysis shows that these hot spots are mostly dominated by Ni d-orbitals. We demonstrate that the Hall coefficient is not well reproduced by Boltzmann transport theory within the constant relaxation time approximation without charge density waves. We consider both uniaxial and biaxial charge density waves and show that biaxial charge density waves can account well for the Hall coefficient, while uniaxial cannot. We also investigate the temperature dependence of the resistivity and the specific heat.