Sleuthing multipolar orders

Quantum magnets with large "spin" can naturally host multipole operators and multipolar symmetry breaking which goes beyond spin dipole order. Such  ordering has been originally proposed in f-electron materials (heavy fermion compounds) where the emergence of multipolar orders has been extensively explored. Probing multipolar orders is challenging due to the intrinsic complexity of the ordering. In this talk, I will describe a bunch of recent experiments on d-orbital Mott insulators which suggest the emergence of robust octupolar order (arising from orbital loop currents) and competing quadrupolar orders. Our theory including microscopics, Landau theory, and Monte Carlo simulations provides a comprehensive understanding of neutron, muon spin rotation, and impurity NMR experiments, and broadens the class of systems which can host multipolar orders.