Magnetic phase transition in antiferromagnetic films

The susceptibility of body-centered cubic lattice (bcc) antiferromagnetic spin-1/2 through two model: Ning and XY films consisting of n = 2. 3, 4. 5, and 6 interacting layers is studied by high-temperature series expansions. Sixth order series in x = beta J (beta = 1/kappa(B)T) have been obtained for free-surface boundary conditions. The high temperature series expansion B of the magnetic susceptibility series has been investigated by using the Pade approximant method. The Neel temperatures T(N)(n) as a function of the number of n spin layers in the films is obtained. The critical exponent gamma associated with the magnetic susceptibility is deduced for Ising and XY models. The shifts of the critical temperatures from the bulk value [T(N)(infinity)/T(N)(n) - 1] can be described by a power law n(-lambda), with lambda = 1/nu where nu is the correlation length exponent. (C) 2009 Published by Elsevier B.V.