title: Global phase diagram and six-state clock universality behavior in the triangular antiferromagnetic Ising model with anisotropic next-nearest-neighbor coupling: level-spectroscopy approach.
abstract: We investigate the triangular-lattice antiferromagnetic Ising model with a spatially anisotropic next-nearest-neighbor ferromagnetic coupling, which was first discussed by Kitatani and Oguchi. By employing the effective geometric factor, we analyze the scaling dimensions of the operators around the Berezinskii-Kosterlitz-Thouless (BKT) transition lines, and determine the global phase diagram. Our numerical data exhibit that two types of BKT-transition lines separate the intermediate critical region from the ordered and disordered phases, and they do not merge into a single curve in the antiferromagnetic region. We also estimate the central charge and perform some consistency checks among scaling dimensions in order to provide the evidence of the six-state clock universality. Further, we provide an analysis of the shapes of boundaries based on the crossover argument.
authors.affiliation: Department of Physics, Tokyo Metropolitan University, Tokyo 192-0397, Japan.
authors.forename: Hiromi
authors.initials: H
authors.lastname: Otsuka
authors.forename: Yutaka
authors.initials: Y
authors.lastname: Okabe
authors.forename: Kiyohide
authors.initials: K
authors.lastname: Nomura