With the variational cumulant expansion (VCE) method, the thermodynamic behaviors of S = 1/2 antiferromagnetic Heisenberg films in simple cubic lattices are studied analytically. From the analytic properties of the free energy, in principle we are able to calculate analytically the critical temperatures Tc(L) and the thermodynamic functions, to any order cumulant as the functions of the number of L (the hyperlayers in the hyperfilm). Explicit expressions for Tc(L) up to the fourth order are given. A comparison with the existing results for 3-dimensional system is given. The effective range of the interaction is obtained from numerical results.
- Antiferromagnetic Heisenberg films
- Variational cumulant expansion method
ASJC Scopus subject areas
- Physics and Astronomy (miscellaneous)