Thermodynamics of the two-dimensional Heisenberg ferromagnet in the framework of the renormalization-group approach

A method of describing the thermodynamic functions of two-dimensional isotropic Heisenberg ferromagnets based on a generalization of the 2 + expansion is proposed. Interpolation formulas constructed in the framework of this approach make possible a smooth passage to the results obtained by the methods of high-temperature expansions.Translated from Teoreticheskaya i Matematicheskaya Fizika, Vol. 104, No. 3, pp. 530–537, September, 1995.