Magnetic properties of antiferromagnetic thin films with spin S

Abstract

The mean field theory (MFT) and high temperature series expansions (HTSEs) of the magnetic susceptibility are used to investigate the magnetic properties in simple cubic (sc) antiferromagnetic with spins S = 1 and S = 3/2 films by using both the Ising and the XY models. The films consisting of l = 2, 3, 4, 5, 6 and infinite (∞) interacting layers are studied up to sixth order series in x = βJ where \(\beta = \tfrac{1} {{k_B T}} \), for free-surface boundary conditions. The effects of finite size on the critical-point behavior are studied by extrapolation of the high-temperature series. The Neel temperature TN(l) as a function of the spin layers numbers l is obtained by using HTSEs of the magnetic susceptibility series, the Pade approximant method and the MFT theory. The critical exponent γ associated with the magnetic susceptibility is deduced. The Neel temperatures TN(l) for the l-layers films are estimated from the divergence of the staggered susceptibility with exponents γ(1) and γ(2) for the Ising and the XY models, respectively. This is consistent with the basic assumptions of scaling laws. The shift exponents of the Neel temperature for the Ising and the XY models, respectively, are estimated.