{
  "id": "1907.03004",
  "version": "v1",
  "published": "2019-07-05T19:19:35.000Z",
  "updated": "2019-07-05T19:19:35.000Z",
  "title": "Magnetization dynamics in clean and disordered spin-1 XXZ chains",
  "authors": [
    "Jonas Richter",
    "Niklas Casper",
    "Wolfram Brenig",
    "Robin Steinigeweg"
  ],
  "comment": "14 pages, 15 figures",
  "categories": [
    "cond-mat.stat-mech",
    "cond-mat.str-el"
  ],
  "abstract": "We study spin transport in the one-dimensional anisotropic S = 1 Heisenberg model. Particular emphasis is given to dynamics at infinite temperature, where current autocorrelations and spatio-temporal correlation functions are obtained by means of an efficient pure-state approach based on the concept of typicality. Our comprehensive numerical analysis unveils that high-temperature spin transport is diffusive in the easy-axis regime for strong exchange anisotropies. This finding is based on the combination of numerous signatures, such as (i) Gaussian spreading of correlations, (ii) a time-independent diffusion coefficient, (iii) power-law decay of equal-site correlations, (iv) exponentially decaying long-wavelength modes, and (v) Lorentzian line shapes of the dynamical structure factor. Moreover, we provide evidence that some of these signatures are not exclusively restricted to the infinite-temperature limit, but can persist at lower temperatures as well, where we complement our results by additional quantum Monte Carlo simulations of large systems. In contrast to the easy-axis regime, we show that in the case of an isotropic chain, the signatures (i) - (v) are much less pronounced or even entirely absent, suggesting the existence of anomalous spin transport despite the nonintegrability of the model. Eventually, upon introducing a random on-site magnetic field, we observe a breakdown of diffusion and distinctly slower dynamics. In particular, our results exhibit qualitative similarities to disordered spin-1/2 chains and might be consistent with the onset of many-body localization in the S = 1 model for sufficiently strong disorder.",
  "revisions": [
    {
      "version": "v1",
      "updated": "2019-07-05T19:19:35.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "magnetization dynamics",
      "xxz chains",
      "additional quantum monte carlo simulations",
      "random on-site magnetic field",
      "easy-axis regime"
    ],
    "note": {
      "typesetting": "TeX",
      "pages": 14,
      "language": "en",
      "license": "arXiv",
      "status": "editable"
    }
  }
}