{
  "id": "cond-mat/0001264",
  "version": "v1",
  "published": "2000-01-19T10:48:05.000Z",
  "updated": "2000-01-19T10:48:05.000Z",
  "title": "Response of non-equilibrium systems at criticality: Ferromagnetic models in dimension two and above",
  "authors": [
    "C. Godreche",
    "J. M. Luck"
  ],
  "comment": "31 pages, 5 figures",
  "journal": "Journal of Physics A 33 (2000), 9141.",
  "doi": "10.1088/0305-4470/33/50/302",
  "categories": [
    "cond-mat.stat-mech"
  ],
  "abstract": "We study the dynamics of ferromagnetic spin systems quenched from infinite temperature to their critical point. We show that these systems are aging in the long-time regime, i.e., their two-time autocorrelation and response functions and associated fluctuation-dissipation ratio are non-trivial scaling functions of both time variables. This is exemplified by the exact analysis of the spherical model in any dimension D>2, and by numerical simulations on the two-dimensional Ising model. We show in particular that, for $1\\ll s$ (waiting time) $\\ll t$ (observation time), the fluctuation-dissipation ratio possesses a non-trivial limit value $X_\\infty$, which appears as a dimensionless amplitude ratio, and is therefore a novel universal characteristic of non-equilibrium critical dynamics. For the spherical model, we obtain $X_\\infty=1-2/D$ for 2<D<4, and $X_\\infty=1/2$ for D>4 (mean-field regime). For the two-dimensional Ising model we measure $X_\\infty\\approx0.26\\pm0.01$.",
  "revisions": [
    {
      "version": "v1",
      "updated": "2000-01-19T10:48:05.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "non-equilibrium systems",
      "ferromagnetic models",
      "two-dimensional ising model",
      "criticality",
      "spherical model"
    ],
    "tags": [
      "journal article"
    ],
    "note": {
      "typesetting": "TeX",
      "pages": 31,
      "language": "en",
      "license": "arXiv",
      "status": "editable"
    }
  }
}