Multipole ordering and fluctuations in -electron systems

Kubo, Katsunori ; Hotta, Takashi

Novel magnetism and exotic superconductivity in actinide compounds have attracted much attention. Among several interesting properties of actinide materials, we review two topics from a microscopic view point. One is multipole ordering in cubic systems, such as peculiar magnetism in NpO. The other topic is a potential role of multipole fluctuations in tetragonal systems. Such fluctuations characteristic to -electron systems may relate to the superconductivity of the so-called Pu-115 materials (PuCoGa and PuRhGa) with relatively high transition temperatures.