In rare-earth pyrochlores such as Tb$_2$Ti$_2$O$_7$, a low-lying crystal-field doublet calls for an effective spin-3/2 description of spin ice. I will show that the resulting competition between single-site anisotropy and exchange produces two topologically distinct Coulomb liquids, selected by the sign of the anisotropy. They have no local order parameter, but differ in their excitations: monopoles are deconfined in one and bound into composite motifs in the other. After a thermal quench, the first relaxes by ordinary monopole diffusion, while the second shows arrested relaxation, a rare example of dynamical arrest in a disorder-free, short-range model. Finally, I discuss the fate of spin-3/2 ice in an external magnetic field along [111]. Unlike ordinary spin-1/2 ice, which shows only a crossover in a [111] field, spin-3/2 ice undergoes a Kasteleyn transition driven by string proliferation.
Zoom link: https://icts-res-in.zoom.us/j/98485310683?pwd=GZDYFsRy80SNb4s8eCxbRgIjT3ZLct.1
Meeting ID: 984 8531 0683
Passcode: 302060