Abstract
We present a numerical study of the many-body localization (MBL) phenomenon in the high-temperature limit within an anisotropic Heisenberg model with random local fields. Taking the dynamical spin conductivity as the test quantity, we investigate the full frequency dependence of sample-to-sample fluctuations and their scaling properties as a function of the system size and the frequency resolution. We identify differences between the general interacting case and the anisotropy , the latter corresponding to the standard Anderson localization. Except for the extreme MBL case when the relative sample-to-sample fluctuations became large, numerical results allow for the extraction of the low- dependence of the conductivity. Results for the dc value indicate a crossover into the MBL regime, i.e., an exponential-like variation with the disorder strength . For the same regime, our numerical analysis indicates that the low-frequency exponent exhibits a small departure from only.
- Received 5 March 2016
- Revised 20 May 2016
DOI:https://doi.org/10.1103/PhysRevB.94.045126
©2016 American Physical Society