Distribution and density of the partition function zeros for the diamond-decorated Ising model

Exact renormalization map of temperature between two successive decorated lattices is given, and the distribution of the partition function zeros in the complex temperature plane is obtained for any decoration level. The rule governing the variation of the distribution pattern as the decoration level changes is given. The densities of the zeros for the first two decoration levels are calculated explicitly, and the qualitative features about the densities of higher decoration levels are given by conjecture. The Julia set associated with the renormalization map is contained in the distribution of the zeros in the limit of infinite decoration level, and the formation of the Julia set in the course of increasing the decoration level is given in terms of the variations of the zero density.