A simple hierarchical scalar spin model is studied analytically and numerically in the vicinity of its critical point. The dependence of the finite size (i.e. calculated for a large but finite number of spins) susceptibility ...

Dynamic susceptibility of the one-dimensional spin-1/2 transverse Ising model is obtained by using the numerical approach suggested earlier [Ferroelectrics 153, 55 (1996)]. The dependence of the susceptibility frequency ...

We consider the pyrochlore-lattice quantum Heisenberg ferromagnet and discuss the properties of this spin model at arbitrary temperatures. To this end, we use the Green’s function technique within the random-phase (or ...