REENTRANT PHASE-TRANSITION IN A PARTICULAR (3X3) UC 2-DIMENSIONAL ISING-MODEL

Abstract

Using the method presented in an earlier paper we obtain the exact partition function per spin, L(T), corresponding to the particular (3 x 3) unitary cell two-dimensional Ising model studied by Kitatani et al. In contrast with these authors that worked with numerical methods, we use algebraic procedures to obtain the analytic expression for L(T), and the exact equation for the critical temperature, T(c), for other values of the interaction parameters. We find results for more extensive ranges of the values of the interaction parameters than obtained by Kitatani et al. We use these results to discuss physical properties of the systems. We exhibit an extended range of values for which double reentrancy is found.