Thermodynamics of the Classical Planar Ferromagnet Close to the Zero-Temperature Critical Point: A Many-Body Approach
Figure 1
Critical line of the classical planar ferromagnet (CPFM) with short-range interactions on a three-dimensional cubic lattice (present work). Here denotes the critical temperature at and the critical magnetic field at . A comparison is shown with the corresponding curves for the classical transverse Ising model (CTIM), obtained by RG calculations, and for the spin-1/2 quantum planar ferromagnet (QPFM). The critical line for the spin- QPFM with long-range interactions in the classical limit has been also obtained at the Tyablikov decoupling level, and, as expected, it coincides with the one calculated for the CPFM.
