An investigation of the high-field series expansions for the square lattice Ising model

Uses high-field series expansions for the square lattice Ising model to investigate the physical singularity in the magnetisation as a function of the field. High-field series were obtained to order 35 at temperatures T approximately=0.5 T c and T approximately=0.766T c using series expansion techniques based on corner transfer matrices. At neither temperature is there any evidence of a spinodal line; the behaviour is consistent with the predictions of the droplet model, suggesting that the first-order transition line is a line of infinitely differentiable singularities.