We present non-equilibrium physics in spin ice as a novel setting which
combines kinematic constraints, emergent topological defects, and magnetic long
range Coulomb interactions. In spin ice, magnetic frustration leads to highly
degenerate yet locally constrained ground states. Together, they form a highly
unusual magnetic state -- a "Coulomb phase" -- whose excitations are pointlike
defects -- magnetic monopoles -- in the absence of which effectively no
dynamics is possible. Hence, when they are sparse at low temperature, dynamics
becomes very sluggish. When quenching the system from a monopole-rich to a
monopole-poor state, a wealth of dynamical phenomena occur the exposition of
which is the subject of this article. Most notably, we find reaction diffusion
behaviour, slow dynamics due to kinematic constraints, as well as a regime
corresponding to the deposition of interacting dimers on a honeycomb lattice.
We also identify new potential avenues for detecting the magnetic monopoles in
a regime of slow-moving monopoles. The interest in this model system is further
enhanced by its large degree of tunability, and the ease of probing it in
experiment: with varying magnetic fields at different temperatures, geometric
properties -- including even the effective dimensionality of the system -- can
be varied. By monitoring magnetisation, spin correlations or zero-field Nuclear
Magnetic Resonance, the dynamical properties of the system can be extracted in
considerable detail. This establishes spin ice as a laboratory of choice for
the study of tunable, slow dynamics.Comment: (16 pages, 13 figures
