Title: Marginal dimensions for multicritical phase transitions
Author(s):

	M. Dudka (Institute for Condensed Matter Physics of the National Academy of Sciences of Ukraine, 1 Svientsitskii St., 79011 Lviv, Ukraine) ,
	R. Folk (Institut für Theoretische Physik, Johannes Kepler Universität Linz, A-4040, Linz, Austria) ,
	Yu. Holovatch (Institute for Condensed Matter Physics of the National Academy of Sciences of Ukraine, 1 Svientsitskii St., 79011 Lviv, Ukraine) ,
	G. Moser (Fachbereich für Materialforschung und Physik, Univerität Salzburg, A-5020 Salzburg, Austria)

The field-theoretical model describing multicritical phenomena with two coupled order parameters with n _|| and n_⊥ components and of O(n_||) ⊕ O(n_⊥) symmetry is considered. Conditions for realization of different types of multicritical behaviour are studied within the field-theoretical renormalization group approach. Surfaces separating stability regions for certain types of multicritical behaviour in parametric space of order parameter dimensions and space dimension d are calculated using the two-loop renormalization group functions. Series for the order parameter marginal dimensions that control the crossover between different universality classes are extracted up to the fourth order in ϵ = 4-d and to the fifth order in a pseudo-ϵ parameter using the known high-order perturbative expansions for isotropic and cubic models. Special attention is paid to a particular case of O(1) ⊕ O(2) symmetric model relevant for description of anisotropic antiferromagnets in an external magnetic field.

Key words: multicritical phenomena, marginal dimensions, renormalization group
PACS: 05.50.+q, 64.60.ae

Full text [pdf, ps]

<< List of papers