Scaling behavior of temperature-dependent thermopower in CeAu2Si2 under pressure

TL;DR

This study investigates the pressure-dependent thermopower and resistivity in CeAu2Si2, revealing a universal scaling behavior linked to Kondo effects and crystal-field splitting, and its relation to superconductivity.

Contribution

It demonstrates a universal thermopower scaling in Ce-based Kondo lattices under pressure and connects thermopower features with superconducting transitions.

Findings

Thermopower follows a universal T/T* scaling up to ~2.

Large negative thermopower minimum precedes superconductivity.

Scaling behavior governed by Kondo coupling and crystal-field effects.

Abstract

We report a combined study of in-plane resistivity and thermopower of the pressure-induced heavy fermion superconductor CeAu2Si2 up to 27.8 GPa. It is found that thermopower follows a scaling behavior in T/T* almost up to the magnetic critical pressure pc ~ 22 GPa. By comparing with resistivity results, we show that the magnitude and characteristic temperature dependence of thermopower in this pressure range are governed by the Kondo coupling and crystal-field splitting, respectively. Below pc, the superconducting transition is preceded by a large negative thermopower minimum, suggesting a close relationship between the two phenomena. Furthermore, thermopower of a variety of Ce-based Kondo-lattices with different crystal structures follows the same scaling relation up to T/T* ~ 2.