title: Stepwise positional-orientational order and the multicritical-multistructural global phase diagram of the s=3/2 Ising model from renormalization-group theory.
abstract: The spin-3/2 Ising model, with nearest-neighbor interactions only, is the prototypical system with two different ordering species, with concentrations regulated by a chemical potential. Its global phase diagram, obtained in d=3 by renormalization-group theory in the Migdal-Kadanoff approximation or equivalently as an exact solution of a d=3 hierarchical lattice, with flows subtended by 40 different fixed points, presents a very rich structure containing eight different ordered and disordered phases, with more than 14 different types of phase diagrams in temperature and chemical potential. It exhibits phases with orientational and/or positional order. It also exhibits quintuple phase transition reentrances. Universality of critical exponents is conserved across different renormalization-group flow basins via redundant fixed points. One of the phase diagrams contains a plastic crystal sequence, with positional and orientational ordering encountered consecutively as temperature is lowered. The global phase diagram also contains double critical points, first-order and critical lines between two ordered phases, critical end points, usual and unusual (inverted) bicritical points, tricritical points, multiple tetracritical points, and zero-temperature criticality and bicriticality. The four-state Potts permutation-symmetric subspace is contained in this model.
authors.affiliation: Department of Physics, Boğaziçi University, Bebek 34342, Istanbul, Turkey.
authors.forename: Çağın
authors.initials: Ç
authors.lastname: Yunus
authors.affiliation: College of Sciences, Koç University, Sarıyer 34450, Istanbul, Turkey.|Department of Physics, Bilkent University, Bilkent 06533, Ankara, Turkey.
authors.forename: Başak
authors.initials: B
authors.lastname: Renklioğlu
authors.affiliation: Department of Physics, Erciyes University, Kayseri 38039, Turkey.
authors.forename: Mustafa
authors.initials: M
authors.lastname: Keskin
authors.affiliation: Faculty of Engineering and Natural Sciences, Sabancı University, Tuzla 34956, Istanbul, Turkey.|Department of Physics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA.
authors.forename: A Nihat
authors.initials: AN
authors.lastname: Berker