{
  "id": "1505.07219",
  "version": "v1",
  "published": "2015-05-27T08:30:44.000Z",
  "updated": "2015-05-27T08:30:44.000Z",
  "title": "Thermodynamics of the frustrated $J_1$-$J_2$ Heisenberg ferromagnet on the body-centered cubic lattice with arbitrary spin",
  "authors": [
    "P. Müller",
    "J. Richter",
    "A. Hauser",
    "D. Ihle"
  ],
  "comment": "19 pages, 10 figures, accepted EPJB",
  "categories": [
    "cond-mat.stat-mech",
    "cond-mat.str-el"
  ],
  "abstract": "We use the spin-rotation-invariant Green's function method as well as the high-temperature expansion to discuss the thermodynamic properties of the frustrated spin-$S$ $J_{1}$-$J_{2}$ Heisenberg magnet on the body-centered cubic lattice. We consider ferromagnetic nearest-neighbor bonds $J_1 < 0$ and antiferromagnetic next-nearest-neighbor bonds $J_2 \\ge 0$ and arbitrary spin $S$. We find that the transition point $J_2^c$ between the ferromagnetic ground state and the antiferromagnetic one is nearly independent of the spin $S$, i.e., it is very close to the classical transition point $J_2^{c,{\\rm clas}}= \\frac{2}{3}|J_1|$. At finite temperatures we focus on the parameter regime $J_2<J_2^c$ with a ferromagnetic ground-state. We calculate the Curie temperature $T_{C}(S,J_{2})$ and derive an empirical formula describing the influence of the frustration parameter $J_{2}$ and spin $S$ on $T_C$. We find that the Curie temperature monotonically decreases with increasing frustration $J_2$, where very close to $J_2^{c,{\\rm clas}}$ the $T_C(J_2)$-curve exhibits a fast decay which is well described by a logarithmic term $1/\\textrm{log}(\\frac{2}{3}|J_1|-J_{2})$. To characterize the magnetic ordering below and above $T_C$, we calculate the spin-spin correlation functions $\\langle {\\bf S}_{\\bf 0} {\\bf S}_{\\bf R} \\rangle$, the spontaneous magnetization, the uniform static susceptibility $\\chi_0$ as well as the correlation length $\\xi$. Moreover, we discuss the specific heat $C_V$ and the temperature dependence of the excitation spectrum. As approaching the transition point $J_2^c$ some unusual features were found, such as negative spin-spin correlations at temperatures above $T_C$ even though the ground state is ferromagnetic or an increase of the spin stiffness with growing temperature.",
  "revisions": [
    {
      "version": "v1",
      "updated": "2015-05-27T08:30:44.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "body-centered cubic lattice",
      "arbitrary spin",
      "heisenberg ferromagnet",
      "transition point",
      "thermodynamic"
    ],
    "note": {
      "typesetting": "TeX",
      "pages": 19,
      "language": "en",
      "license": "arXiv",
      "status": "editable"
    }
  }
}