Phase transition in the singularity spectrum of an intermingled basin.

A two-dimensional piecewise linear mapping is introduced as a solvable model to characterize the multifractal structure of an intermingled basin. To this end, we make use of the multifractal formalism and introduce a partition function. The singularity spectrum, which characterizes local scaling property of the intermingled basin, is then determined. We have found that if the system is not symmetric, the singularity spectrum of either basin shows a phase transition, corresponding to the existence of two phases the orbits experience in the system, i.e., local one governed by the chaotic motions on the chaotic attractor, and the other global one reflecting nonhyperbolic motions characteristic of the intermingled basin.