{
  "id": "0912.4431",
  "version": "v1",
  "published": "2009-12-22T15:51:29.000Z",
  "updated": "2009-12-22T15:51:29.000Z",
  "title": "Specific heat of stage-2 MnCl$_{2}$ graphite intercalation compound: co-existence of spin glass phase and incommensurate short-range spin order",
  "authors": [
    "Masatsugu Suzuki",
    "Itsuko S. Suzuki",
    "Tadashi Adachi",
    "Yoji Koike"
  ],
  "comment": "14 pages, 20 figures",
  "categories": [
    "cond-mat.dis-nn"
  ],
  "abstract": "Stage-2 MnCl$_{2}$ GIC magnetically behaves like a quasi 2D $XY$ antiferromagnet on the triangular lattice. It shows a typical spin glass behavior below the spin freezing temperature $T_{SG}$ (= 1.1 K). The AC magnetic susceptibility shows a peak at $T$ = $T_{SG}$ at $H$ = 0. This peak shifts to the low temperature side with increasing $H$, according to the de Almeida-Thouless critical line. We have undertaken an extensive study on the $T$ dependence of specific heat in the absence of an external field $H$ and in the presence of $H$ along the $c$ plane. The magnetic specific heat $C_{mag}$ at $H$ = 0 shows no anomaly at $T_{SG}$, but exhibits double broad peaks around 5 K and 41 K. The magnetic specific heat $C_{mag}$ at $H$ = 0 is described by $C_{mag} \\propto (1/T^{2})\\exp(-\\Delta/T)$ with $\\Delta = 1.41 \\pm 0.03$ K, while $C_{mag}$ at $H$ = 10 kOe is proportional to $T$. The entropy due to the broad peak around 5 K is 1/3 of the total entropy. The residual entropy is 63 % of the total entropy because of highly frustrated nature of the system. The magnetic neutron scattering indicates that a short range spin order associated with the incommensurate wave vector $| {\\bf Q}_{incomm}|$ ($= 0.522 \\AA^{-1}$ at 0.45 K) appears below 5 K and remains unchanged down to 63 mK. The in-plane spin correlation length is only 18 $\\AA$ at 0.45 K. The low temperature phase below $T_{SG}$ is a kind of reentrant spin glass phase where the spin glass phase coexists with a short range spin order associated with $| {\\bf Q}_{incomm}|$.",
  "revisions": [
    {
      "version": "v1",
      "updated": "2009-12-22T15:51:29.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "spin glass phase",
      "incommensurate short-range spin order",
      "specific heat",
      "graphite intercalation compound",
      "short range spin order"
    ],
    "note": {
      "typesetting": "TeX",
      "pages": 14,
      "language": "en",
      "license": "arXiv",
      "status": "editable",
      "adsabs": "2009arXiv0912.4431S"
    }
  }
}