Abstract
We have studied the phase transition of the Ising model on a family of fractals called Nice trees whose spectral dimension ds can take values greater than 2. The phase transition is shown to be the trivial zero-temperature one through exactly solving the free energy and the spontaneous magnetization of the system, and is different from that on Cayley trees. The result is independent of ds of the structure and hence provides an example of trivial phase transition at ds>or=2, which does not agree with the argument of Yu and Gong (1994). It suggests that the role of ds in determining the phase transition may be complex.