Theoretical Investigation of Anomalous Hall and Nernst Responses in Potassium Tri Vanadium Pentantimonide

TL;DR

This paper provides a theoretical analysis of anomalous Nernst and Hall effects in potassium tri vanadium pentantimonide, revealing temperature-dependent behaviors, sensitivity to chemical potential, and topological features related to Berry curvature and Chern numbers.

Contribution

It introduces a comprehensive theoretical model incorporating complex hopping, spin-orbit coupling, and magnetic effects to explain anomalous transport phenomena in the Kagome metal.

Findings

Nernst conductivity peaks at certain temperatures and is sensitive to chemical potential shifts.

Multiple bands exhibit nonzero Berry curvature with weak topological features.

Introducing momentum-dependent phases induces opposite Chern numbers in some bands.

Abstract

We present a theoretical study of the anomalous Nernst and Hall conductance in the Kagome metal potassium tri vanadium pentantimonide, based on a system Hamiltonian incorporating nearest neighbour and complex next nearest neighbour hopping, Rashba spin orbit coupling, an exchange field induced by magnetic proximity, and a charge density wave potential. Our analysis reveals that the Nernst conductivity exhibits a non monotonic temperature dependence. It increases with temperature, reaches a pronounced peak, and subsequently declines at higher temperatures due to thermal broadening, which diminishes the influence of Berry curvature. Notably, small shifts in the chemical potential can lead to dramatic changes in the Nernst signal enhancing its magnitude or even reversing its sign highlighting the system sensitivity to carrier density. We further explore the anomalous Hall behaviour within this framework. The band structure hosts multiple bands with nonzero Berry curvature, and preliminary Chern number calculations suggest weak topological features, namely, while not fully quantized, the system exhibits significant Berry curvature accumulation. Upon introducing momentum space winding, implemented via a momentum dependent phase in the complex hopping terms to mimic orbital magnetic flux, we observe that two bands acquire opposite Chern numbers. The remaining bands remain topologically trivial.