title: Phase diagram of a truncated tetrahedral model.
abstract: Phase diagram of a discrete counterpart of the classical Heisenberg model, the truncated tetrahedral model, is analyzed on the square lattice, when the interaction is ferromagnetic. Each spin is represented by a unit vector that can point to one of the 12 vertices of the truncated tetrahedron, which is a continuous interpolation between the tetrahedron and the octahedron. Phase diagram of the model is determined by means of the statistical analog of the entanglement entropy, which is numerically calculated by the corner transfer matrix renormalization group method. The obtained phase diagram consists of four different phases, which are separated by five transition lines. In the parameter region, where the octahedral anisotropy is dominant, a weak first-order phase transition is observed.
authors.affiliation: Institute of Physics, Slovak Academy of Sciences, SK-845 11, Bratislava, Slovakia.
authors.forename: Roman
authors.initials: R
authors.lastname: Krcmar
authors.affiliation: Institute of Physics, Slovak Academy of Sciences, SK-845 11, Bratislava, Slovakia.
authors.forename: Andrej
authors.initials: A
authors.lastname: Gendiar
authors.affiliation: Department of Physics, Graduate School of Science, Kobe University, Kobe 657-8501, Japan.
authors.forename: Tomotoshi
authors.initials: T
authors.lastname: Nishino