Thermal and electronic properties of rare earth compounds at high pressure

Abstract Electronic properties of rare earth metals, alloys and intermetallic compounds have attracted a lot of attention not only from the viewpoint of fundamental aspects but also from the application. These materials show a wide variety of electronic and magnetic properties, such as magnetic order, superconductivity, intermediate valence, Kondo effect and so forth. In this chapter we introduce a lot of experimental studies about the effect of pressure on the thermal, structural and electronic properties of rare earth compounds, in which the electronic states are marginal due to unstable 4f electrons. We describe the present status in this research area. In section 2, the relations between crystal structure and electronic and magnetic state by using X-ray and neutron diffraction under pressure are reported. Effect of pressure on the thermal properties mainly for heavy fermions are reported in section 3. Novel pressure-induced electronic phase transitions such as the crossover in the electronic states and superconductivity are introduced for several heavy fermion materials in section 4. In the last section 5, we show miscellaneous examples which are found recently for amorphous state rare earth compounds and rare earth magnetic multilayers.