Multiband effects in thermoelectric and electrical transport properties of kagome superconductors $A$V$_3$Sb$_5$ ($A$ = K, Rb, Cs)

TL;DR

This study investigates how multiband electronic structures influence thermoelectric and electrical transport in kagome superconductors $A$V$_3$Sb$_5$, revealing sign changes and ambipolar effects in their normal state.

Contribution

It provides the first detailed analysis of multiband effects on transport properties in $A$V$_3$Sb$_5$ superconductors, highlighting sign reversals and ambipolar transport phenomena.

Findings

Sign changes in Seebeck and Hall resistivity with temperature.

Ubiquitous ambipolar transport effects and sizable Nernst signals.

Discussion of possible origins for Hall effect sign reversal.

Abstract

We studied the effects of multiband electronic structure on the thermoelectric and electrical transport properties in the normal state of kagome superconductors $A$V$_3$Sb$_5$ ($A$ = K, Rb, Cs). In all three members, the multiband nature is manifested by sign changes in the temperature dependence of the Seebeck and Hall resistivity, together with sublinear response of the isothermal Nernst and Hall effects to external magnetic fields in the charge ordered state. Moreover, ambipolar transport effects appear ubiquitously in all three systems, giving rise to sizable Nernst signal. Finally, possible origins of the sign reversal in the temperature dependence of the Hall effect are discussed.