On the critical dynamics of extended-impurity systems in cubic anisotropic crystals

Critical dynamics is studied for N-component spin systems in cubic anisotropic crystals in the presence of extended impurities, namely εd-dimensionally connected impurities distributed randomly in d∼ (≡ d − εd) dimensions (d: dimensionality of the medium; d ≡ 4 - ε). As extended impurities make the systems coordinate-anisotropic, new results are expected in the critical dynamics. By means of a field-theoretic renormalization-group (RG) approach, critical regions and dynamic critical exponents are evaluated, to the lowest order in a double ε, εd expansion, for models corresponding to model A, model B and model C, proposed by Hohenberg and Halperin.