New results are presented for the wavevector-dependent susceptibility of Z-invariant periodic and quasiperiodic Ising models in the scaling limit, generalizing old results of Tracy and McCoy for the square lattice. Explicit results are worked out for the two leading singular terms of the...

The magnetic properties of a transverse Ising thin film are investigated by the use of the two theoretical frameworks, namely the standard mean-field theory and the effective field theory better than the mean-field theory. Some new aspects of the magnetic properties have been clarified firstly...

The magnetic properties (phase diagram, magnetization curve, spin correlation functions, internal energy and magnetic specific heat) of a decorated ferrimagnetic square lattice composed of three magnetic atoms are investigated on the basis of the differential technique. The system can show many...

Exact and/or rigorous results are reviewed for the Ising and XY/Villain spin glasses in finite dimensions, such as the exact energy, correlation identities and a functional relation between the distribution functions of ferromagnetic and spin glass order parameters. This last relation is useful...