This Colloquium reviews the 25 year quest to understand the continuous (second-order),
mean-field-like phase transition occurring at 17.5 K in URu 2 Si 2. About ten years ago, the …

This topical review describes the multitude of unconventional behaviors in the hidden order,
heavy fermion, antiferromagnetic and superconducting phases of the intermetallic …

Recent advances on ferromagnetic superconductors, UGe 2, URhGe and UCoGe are
presented. The superconductivity (SC) peacefully coexists with the ferromagnetism (FM) …

Exotic electronic states resulting from entangled spin and orbital degrees of freedom are
hallmarks of strongly correlated f-electron systems. A spectacular example is the so-called …

The development of collective long-range order by means of phase transitions occurs by the
spontaneous breaking of fundamental symmetries. Magnetism is a consequence of broken …

Throughout the past three decades, the hidden order (HO) problem in URu2Si2 has
remained a 'hot topic'in the physics of strongly correlated electron systems with well over …

The multipole concept, which characterizes the spacial distribution of scalar and vector
objects by their angular dependence, has already become widely used in various areas of …

We have performed magnetic torque and resistivity measurements on the centrosymmetric
skyrmion host GdRu 2 Si 2, in which the dominant magnetic interaction leading to skyrmion …

We report angle-resolved photoemission spectroscopy experiments probing deep into the
hidden-order state of URu 2 Si 2, utilizing tunable photon energies with sufficient energy and …

An antiferro ordering of an electric hexadecapole moment is discussed as a promising
candidate for the long standing mystery of the hidden order phase in URu 2 Si 2. Based on …