Phase transitions in gauge coupled systems

Thesis/Dissertation · Sat Dec 31 23:00:00 EST 1977

OSTI ID:6444591

Chen, J H

The renormalization group approach is used to study a special universality class in which the order parameter is coupled to a gauge field. Besides the global symmetry there is the local symmetry associated with the gauge coupling. Mean field theory predicts a second order transition, however, fluctuations of the gauge field coupling to the order parameter lead to a slightly first order transition in most instances. Among the statistical mechanical systems which belong to this universality group, we study the transition from normal metal to superconductor and the transition from the nematic phase to the smectic-A phase in liquid crystals. For the case of liquid crystals, a phenomenological model, the NAC model is developed which exhibits a nematic to smectic-A (NA) transition, a nematic to smectic-C (NC) transition, and a Lifshitz point. The NAC model is used to calculate fluctuation enhancements of elastic constants for the NA and NC transitions and for the Lifshitz point. For the NC transition, all three elastic constants diverge as xi/sup 2/, where xi is the correlation length of the order parameter. At the Lifshitz point, K/sub 1/ and K/sub 2/ diverge as ln xi whileas K/sub 3/ diverges as xi. For the case of superconductor, crossover behavior in the vicinity of the fluctuation induced first order transition is studied using the renormalization group epsilon-expansion. The deviation of the transition temperature from the limit of metastability of the disordered phase from above is found to be somewhat smaller than predicted by naive scaling.

• Research Organization: Pennsylvania Univ., Philadelphia (USA)
• OSTI ID: 6444591
• Country of Publication: United States
• Language: English

Related Subjects

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71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
CRYSTALS
FIELD THEORIES
FLUIDS
GROUP THEORY
LIQUIDS
MATHEMATICS
PHASE TRANSFORMATIONS
PHYSICAL PROPERTIES
RENORMALIZATION
SUPERCONDUCTORS
SYMMETRY
THERMODYNAMIC PROPERTIES
TRANSITION TEMPERATURE