Probing the phase diagram of CeRu_2Ge_2 by thermopower at high pressure

TL;DR

This study investigates how pressure influences the thermopower and resistivity of CeRu_2Ge_2, revealing a transition from magnetic order to intermediate-valent behavior and analyzing the Kondo temperature evolution.

Contribution

It provides a detailed high-pressure phase diagram of CeRu_2Ge_2 based on thermopower and resistivity measurements, highlighting the evolution of electronic states.

Findings

Magnetic order is suppressed at approximately 6.4 GPa.

A large positive maximum in thermopower develops above 10 K at intermediate pressures.

The pressure dependence of the Kondo temperature T_K is characterized.

Abstract

The temperature dependence of the thermoelectric power, S(T), and the electrical resistivity of the magnetically ordered CeRu_2Ge_2 (T_N=8.55 K and T_C=7.40 K) were measured for pressures p < 16 GPa in the temperature range 1.2 K < T < 300 K. Long-range magnetic order is suppressed at a p_c of approximately 6.4 GPa. Pressure drives S(T) through a sequence of temperature dependences, ranging from a behaviour characteristic for magnetically ordered heavy fermion compounds to a typical behaviour of intermediate-valent systems. At intermediate pressures a large positive maximum develops above 10 K in S(T). Its origin is attributed to the Kondo effect and its position is assumed to reflect the Kondo temperature T_K. The pressure dependence of T_K is discussed in a revised and extended (T,p) phase diagram of CeRu_2Ge_2.