High-rank multipole ordering in f-electron systems

Kambe, Shinsaku  

Recently found high-rank multipolar ordering in -electron systems will be reviewed. For example, (1) odd parity rank-5 (electric dotriacontapole) ordering is likely in URuSi, which is known as "hidden ordering"; (2) even parity rank-3 (magnetic octupole) ordering in NpO is now well-established. Such a high-rank multipolar ordering with high symmetry is sensitive to symmetry-breaking field and change of relevant interaction. Therefore, comparing to usual dipolar ordering, there are various spin and orbital concerned responses of multipolar ordering to external field magnetic field, pressure, uni-axial stress etc. Some examples of these responses will be addressed.