Critical dynamics of Heisenberg antiferromagnets: Correlation functions above Néel point

Theory describing critical behavior of isotropic Heisenberg antiferromagnets (AF) is proposed for a temperature range above the Neel point. It is shown that the critical dynamics of AF should be described in terms of relaxation-diffusion mode coupling and the scaling behavior of spin diffusion coefficient is determined by the scaling law for relaxation kinetic coefficient. The method based on analysis of diagrammatic expansion for diffusion and relaxation constants allows incorporation of nonlocal spin-liquid correlations. Applications of the method to heavy-fermion (HF) materials are briefly discussed.