title: Tricritical point of the J1-J2 Ising model on a hyperbolic lattice.
abstract: The ferromagnetic-paramagnetic phase transition of the two-dimensional frustrated Ising model on a hyperbolic lattice is investigated by use of the corner transfer matrix renormalization group method. The model contains a ferromagnetic nearest-neighbor interaction J1 and a competing antiferromagnetic interaction J2 . A mean-field-like second-order phase transition is observed when the ratio kappa=J_{2}J_{1} is less than 0.203. In the region 0.203<kappa<14 , the spontaneous magnetization is discontinuous at the transition temperature. Such tricritical behavior suggests that the phase transitions on hyperbolic lattices need not always be mean-field-like.
authors.affiliation: Institute of Electrical Engineering, Centre of Excellence CENG, Slovak Academy of Sciences, Dúbravská cesta 9, SK-841 04, Bratislava, Slovakia.
authors.forename: R
authors.initials: R
authors.lastname: Krcmar
authors.forename: T
authors.initials: T
authors.lastname: Iharagi
authors.forename: A
authors.initials: A
authors.lastname: Gendiar
authors.forename: T
authors.initials: T
authors.lastname: Nishino