Sublinear transport in Kagome metals: Interplay of Dirac cones and Van Hove singularities

TL;DR

This paper develops a semiclassical theory to explain sublinear resistivity in Kagome metals, highlighting the role of Dirac cones, Van Hove singularities, and electron interactions, and predicts violations of the Wiedemann-Franz law.

Contribution

It introduces a minimal two-pocket model and a semiclassical Boltzmann approach to elucidate transport phenomena in Kagome metals, linking electronic structure to experimental observations.

Findings

Internode electron-electron interactions cause sublinear T scaling in resistivity.

Distinct scattering channels at higher T lead to Wiedemann-Franz law violation.

The theory aligns with experimental data on Ni₃In and similar Kagome metals.

Abstract

Kagome metals are known to host Dirac fermions and saddle point Van Hove singularities near Fermi level. With the minimal two-pocket model (Dirac cone + Van Hove singularity), we propose a semiclassical theory to explain the experimentally observed sublinear resistivity in Ni$_3$In and other Kagome metals. We derive the full semiclassical description of kinetic phenomena using Boltzmann equation, and demonstrate that internode electron-electron interaction leads to sublinear in $T$ scaling for both electrical and thermal transport at low temperatures. At higher temperatures above the Dirac node chemical potential, thermal and electric current dissipate through distinct scattering channels, making a ground for Wiedemann-Franz law violation.