Tunable Non-Equilibrium Dynamics of Quenches in Spin Ice

When: Friday, February 28, 2014 at 12:00 pm
Where: DA 114
Speaker: Claudio Castelnovo
Organization: University of Cambridge
Sponsor: Condensed Matter Seminar

Tunable non-equilibrium dynamics of quenches in spin ice We present non-equilibrium physics in spin ice as a unique setting that 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 point-like 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. Most notably, we find reaction diffusion behaviour, slow dynamics owing to kinematic constraints, as well as a regime corresponding to the deposition of interacting dimers on a honeycomb lattice. The interest in this model system is further enhanced by its large degree of tunability and the ease of pro bing it i n experiment: With varying magnetic fields at different temperatures, geometric properties — including even the effective dimensionality of the system — can be varied. By monitoring magnetization, spin correlations or zero-field NMR, 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.

Host: Assistant Professor Adrian Feiguin