Heavy fermions and unconventional superconductivity in high-quality single crystals of rare-earth and actinide compounds

Abstract

The f-electron system in rare-earth and actinide compounds exhibit a variety of characteristic properties including heavy fermions and unconventional superconductivity. The Fermi surface properties in rare-earth and actinide compounds are clarified by the de Haas-van Alphen experiments on the basis of the results of energy band calculations. The effect of pressure on the electronic states of CeRhIn5, CeIrSi3, and YbIr2Zn20 is studied in magnetic fields. An electronic instability, including unconventional superconductivity, occurs at 2.4 GPa in CeRhIn5 and 2.6 GPa in CeIrSi3. An abrupt non-linear increase in the magnetization, namely, a metamagnetic behavior, is found in the heavy fermion compounds, including YbT2Zn20 (T: Co, Rh, Ir). A super-heavy fermion state with a specific heat coefficient of 10 J/(K2·mol) is realized in YbIr2Zn20 under pressure.