Study of the critical behaviour of three-dimensional Ising-like systems on the basis of the rho(6) model with allowance for microscopic parameters: II. Low-temperature region

摘要

A microscopic approach to the investigation of the three-dimensional Ising-like system thermodynamics below the phase transition temperature T, is schematically presented within the framework of the higher non-Gaussian approximation (rho(6) model) taking into account the corrections to scaling. A microscopic analogue of the Landau free energy is calculated. Explicit expressions for the thermodynamic characteristics are obtained as functions of the temperature and microscopic parameters of the system. The thermodynamic characteristics near T, and their amplitudes are given for various values of the effective radius of the exponentially decreasing interaction potential (including the values corresponding to the nearest-neighbour interaction, the interaction between the nearest and next-nearest neighbours, and that between the nearest, next-nearest, and third neighbours). The evolutions of the free energy of the system at the phase transition point, average spin moment, and specific heat with increasing ratio of the potential effective radius to the simple cubic lattice constant are plotted. The results of calculations and their comparison with other authors' data show that the rho(6) model provides a better quantitative description of the critical behaviour of a three-dimensional Ising magnetic than the rho(4) model. [References: 29]