The two-layer Ising model on a sequence of diamond-like hierarchical lattices

Abstract

The two-layer Ising model on diamond-like hierarchical lattices of different structures with equal fractal dimension was investigated. We applied the renormalization group transformations for the considered lattices. The critical values of the shift exponent φ were computed for various intralayer interaction values (J1 and J2). For the simplest diamond-like hierarchical lattice φ≈2.35 at J1=J2. As the structure of the lattice becomes more complex, the shift exponent value increases. At J1=0.5J2 the value φ≈0.5 was obtained, which is consistent with the data for the square lattice. The graphs of the heat capacity, magnetization and magnetic susceptibility were plotted at J1=0.5J2. They showed the absence of the second phase transition at an arbitrarily weak coupling between the layers.