The Pair Approximation method is applied to studies of the bilayer and multilayer magnetic systems with simple cubic structure. The method allows to take into account quantum effects related to non-Ising couplings. The paper adopts the anisotropic Heisenberg model for spin S=1/2 and considers...

We theoretically study physical properties of solutes placed in a straight line and at regular intervals. The solute is a rigid-body and has an arrow-like shape, which changes its direction up (↑) or down (↓). If the rigid solutes are immersed in a continuum solvent, nothing happens in the...

We propose a general method by which a spin-S is decomposed into spins less than S. We have obtained the exact mapping between spin S=pM−12 and a cluster of M spins σ=p−12, where p and M are positive integers. We have discussed the possible applications of such transformations. In...