Tricritical Behavior in Two Dimensions.

The onset of two dimensional tricritical behavior in N x infinity strips of spins in an Ising-like model is investigated. This is done through numerical computation of the largest eigenvalue of the single spin advance transfer matrix. Primary attention is paid to the specific heat at constant non-ordering field. The usual phase diagram, in zero ordering field, locates the tricritical point at the intersection of a first order line and a lambda line; it is found here that a curve of large field, bounded and rounded specific heat peaks also seems to intersect this point. This curve, when it exists, may be helpful in experimentally locating tricritical points in any dimension. Evidence is also presented, in zero non-ordering field, for the validity of the Onsager specific heat temperature shift, N to the minus 2 power in N, in the model.