Slow dynamics in classical and quantum spin ice systems

The low temperature properties of magnetic systems with fractionalised point-like excitations are determined by the interplay between a small density of quasiparticles and the underlying spin degrees of freedom out of which they are borne. Spin ice materials are a case in point. Even in their simplest classical modelling, a dramatic slowing down is expected due to the excitations becoming exponentially sparse. Once more realistic details are taken into account, and in particular quantum fluctuations are included, the situation becomes far more complex and interesting. The phenomenology uncovered thus far includes the formation of long-lived metastable states, structural as well as correlation-driven disorder that alters the local quantum mechanical spin fluctuations, and a prominent freezing of the dynamics whose origin continues to elude our understanding. This talk presents a selection of results and observations that highlight the uniquely rich, tunable and experimentally accessible playground to study slow dynamics in frustrated magnetism offered by spin ice systems.