Effects of ferromagnetic fluctuations on the electric and thermal transport properties in NaxCoO2

TL;DR

This study explores how ferromagnetic fluctuations influence the electronic and transport properties of NaxCoO2, revealing their significant role in shaping resistivity, thermoelectric power, and magnetic susceptibility.

Contribution

It provides a theoretical analysis of ferromagnetic fluctuation effects on transport properties in NaxCoO2 using a two-dimensional d-p model and fluctuation exchange approximation.

Findings

Effective mass and resistivity increase with x > 0.6

Thermoelectric power and spin susceptibility also increase with x > 0.6

Results align qualitatively with experimental observations

Abstract

We investigate the electronic states and the transport properties of the CoO2 plane in NaxCoO2 on the basis of the two-dimensional triangular lattice 11-band d-p model by using the fluctuation exchange approximation, where we consider the Coulomb interaction between the t2g electrons on a Co site. It is found that all of the effective mass of quasiparticles, the resistivity, the thermoelectric power and the uniform spin susceptibility increase with increasing x for x > 0.6. This implies that the ferromagnetic fluctuations play significant roles on determining the electronic states. These results are qualitatively consistent with the experiments.