Phase diagrams for the triangular Ising lattice with re-entrant ferromagnetism

Vladimir Iglovikov, J. Oitmaa, Rajiv R. P. Singh +1 more

Vadim A. Mutailamov, Akai Kurbanovich Murtazaev

Ken‐Yu Lin, Fa Yueh Wu

L Toth, Monika Tóthová

Using the finite-cluster approximation and renormalization technique the authors study the spin-1/2 Ising model for a simple-cubic lattice with nearest-neighbour random interactions. They consider nearest-neighbour ferromagnetic exchange interactions J with concentration 1-p and exchange interactions alpha J(|alpha|1) with concentration p. The phase diagrams were obtained for this model. They show re-entrant behaviour in certain ranges of the concentration p and different alpha .

E. E. Reinehr, W. Figueiredo

Jukka A. Ketoja, Indubala I. Satija

We study the phase diagram of the tight-binding model for an electron on an anisotropic square lattice with a four-dimensional parameter space defined by two nearest-neighbour and two next-nearest-neighbour couplings. Using a renormalization scheme, we show that the inequality of the two next-nearest-neighbour couplings destroys the fat critical regime found in the isotropic case above the bicritical line and replaces it with another re-entrant extended phase. The scaling properties of the model are those of the corresponding tight-binding models on the nearest-neighbour square and triangular lattices. The triangular universality class also describes the quantum Ising chain in a transverse field with the only exception being the conformally invariant state of the Ising model which has no analogue in the triangular-lattice case.