Abstract
We consider the isotropic Heisenberg chain with a finite Haldane gap and use state-of-the-art numerical techniques to investigate its dynamical properties at finite temperature, focusing on the nuclear spin-lattice relaxation rate measured in nuclear magnetic resonance (NMR) experiments, for instance. In particular, we analyze the contributions from modes with momenta close to and as a function of temperature. At high-temperature we observe spin diffusion, while at low-temperature we argue that a simple activated behavior can be observed only at temperatures much smaller than the gap .
- Received 11 June 2019
DOI:https://doi.org/10.1103/PhysRevB.100.094411
©2019 American Physical Society