ZEROS OF THE PARTITION-FUNCTION FOR HIGHER-SPIN 2D ISING-MODELS

We present calculations of the complex-temperature zeros of the partit ion functions. for 2D Ising models on the square lattice with spin s = 1, 3/2 and 2. These give an insight into complex-temperature phase di agrams of these models in thermodynamic limit. Support is adduced for a conjecture that all divergences of the magnetization occur at endpoi nts of arcs of zeros protruding into the FM phase. We conjecture that there are 4[s(2)] - 2 such arcs for s greater than or equal to 1, wher e [x] denotes the integral part of x.