Unified description of resistivity and thermopower of Pr$_2$Ir$_2$O$_7$: possible influence of crystal field excitation in a Kondo lattice

TL;DR

This study investigates the resistivity and thermopower behaviors of Pr$_2$Ir$_2$O$_7$, highlighting incoherent Kondo scattering and crystal field effects as key factors influencing its electronic properties.

Contribution

It provides experimental evidence linking incoherent Kondo scattering and crystal field excitations to transport phenomena in Pr$_2$Ir$_2$O$_7$, a novel insight into its electronic behavior.

Findings

Resistivity minima caused by incoherent Kondo scattering.

Thermopower shows a high-temperature positive maximum and a low-temperature negative minimum.

Weak correlation between Kondo temperature and intersite coupling strength.

Abstract

We present experimental evidence of incoherent Kondo scattering as the source of resistivity minima in bulk polycrystalline and nanocrystalline Pr$_2$Ir$_2$O$_7$. The temperature dependence of thermopower shows a positive maximum at high temperature followed by a negative minimum at low temperature, with the sign inversion occurring at a much higher temperature than $T_K$. Moreover, we observe little correlation between TK and intersite coupling strength given by $\theta_{CW}$. We describe the temperature dependence of thermopower and resistivity within the framework of crystal field excitation in a Kondo lattice.