Recent Advances in the 5f-Relevant Electronic States and Unconventional Superconductivity of Actinide Compounds

Abstract

Recent advances in the understanding of the 5f-relevant electronic states and unconventional superconducting properties are reviewed in actinide compounds of UPd₂Al₃, UPt₃, URu₂Si₂, UGe₂, and PuRhGa₅. These are based on the experimental results carried out on high-quality single crystal samples, including transuranium compounds, which were grown by using combined techniques. The paring state and the gap structure of these superconductors are discussed, especially for the corresponding Fermi surfaces which were clarified by the de Haas–van Alphen experiment and the energy band calculations. A detailed systematic study using the NQR/NMR spectroscopy reveals the d-wave superconductivity in PhRhGa₅ and the difference of magnetic excitations due to the difference of ground states in U-, Np-, and Pu-based AnTGa₅ (T: transition metal) compounds.