paper

Critical behavior of certain antiferromagnets with complicated ordering: Four-loop $\ve$-expansion analysis

arXiv:cond-mat/0111330 · doi:10.1103/PhysRevB.64.214423

Abstract

The critical behavior of a complex N-component order parameter Ginzburg-Landau model with isotropic and cubic interactions describing antiferromagnetic and structural phase transitions in certain crystals with complicated ordering is studied in the framework of the four-loop renormalization group (RG) approach in $(4-\ve)$ dimensions. By using dimensional regularization and the minimal subtraction scheme, the perturbative expansions for RG functions are deduced and resummed by the Borel-Leroy transformation combined with a conformal mapping. Investigation of the global structure of RG flows for the physically significant cases N=2 and N=3 shows that the model has an anisotropic stable fixed point governing the continuous phase transitions with new critical exponents. This is supported by the estimate of the critical dimensionality obtained from six loops via the exact relation established for the complex and real hypercubic models.

LaTeX, 16 pages, no figures. Expands on cond-mat/0109338 and includes detailed formulas

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