Physical Review B

Beyond fragmented dopant dynamics in quantum spin lattices: Robust localization and non-Gaussian diffusion

In this work, the authors study in great detail how a single charge moves in a thermal spin background using state-of-the-art tensor network calculations. While hydrodynamic arguments suggest that charges and spins generically diffuse at high temperatures, the authors identify a regime in which the charge remains localised. This arises, when the spins interact classically and gives rise to an emergent random energy landscape experienced by the charge, akin to the Anderson localization effect, and generalizes previous studies by one of the authors on Hilbert-space fragmented models.

Moreover, they demonstrate that even when diffusion is present in the system, it is highly non-trivial. Indeed, they show that the scaling behavior of the transport is non-Gaussian, whereby a simple hydrodynamic diffusion equation cannot explain the observations. Moreover, they show that as the system is cooled, diffusion slows down exponentially and is well-described by an so-called Arrhenius relation. 

Access to paper :https://journals.aps.org/prb/abstract/10.1103/clhr-4h26