Probing the phase diagram of CeRu₂Ge₂ by thermopower at high pressure

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The temperature dependence of the thermoelectric power, S(T), and the electrical resistivity of the magnetically ordered CeRu₂Ge₂ (Tₙ=8.55 K and TC=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 pc 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 Tₖ. The pressure dependence of Tₖ is discussed in a revised and extended (T,p) phase diagram of CeRu₂Ge₂.