Diffusion and relaxation of topological excitations in layered spin liquids
Year: 2026
Type: article
Abstract: Relaxation processes in topological phases such as quantum spin liquids are controlled by the dynamics and interaction of topological excitations. In layered materials hosting two-dimensional topological order, elementary quasiparticles can diffuse freely within the layer, whereas only pairs (or more) can hop between layers - a fundamental consequence of topological order. Using exact solutions of emergent nonlinear classical diffusion equations and particle-based stochastic simulations, we explore how pump-probe experiments can provide unique signatures of the presence of 2d 2 d topological excitations in a layered 3d 3 d material. Here we show that the characteristic time scale of such experiments is inversely proportional to the initial excitation density, set by the pump intensity. A uniform excitation density created on the surface of a sample spreads subdiffusively into the bulk with a mean depth \bar z z ‾ scaling as \sim t^{1/3} ∼ t 1 / 3 when annihilation processes are absent. The propagation becomes logarithmic, \bar z \sim \log t z ‾ ∼ log t , when pair-annihilation is allowed. Furthermore, pair-diffusion between layers leads to a new decay law for the total density, n(t) \sim (\log^2 t)/t n ( t ) ∼ ( log 2 t ) / t - slower than in a purely 2d 2 d system. We discuss possible experimental implications for pump-probe experiments in finite-size systems.
Source: SciPost Physics
Authors: Aprem P. Joy, Roman Lange, Achim Rosch
Institution: University of Cologne
Language: English
Subfield: Condensed Matter Physics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: diamond
OpenAlex ID: W7165933194