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Manifestations of symmetry and internal phases in unconventional superconductors

Thesis/Dissertation ·
OSTI ID:6982303

A study of unconventional superconductivity is presented. The general Ginzburg-Landau approach based on the broken symmetry is reviewed. By introducing the coupling between the antiferromagnetic and superconducting ordering which belongs to the [sup 1]E[sub g] representation of the D[sub 4h] group, we obtain nine possible phase diagrams of the heavy fermion superconductor URu[sub 2]Si[sub 2] in the H-T plane. The domain wall formed by two time reversed states of the mixture order parameter belonging to A[sub 1g] [+-] iB[sub 1g] representation of the tetragonal group results in a weak superconducting region which acts as a carrier against the current flow by having a lower critical density than bulk. The orientation dependence of the Josephson current is studied. The current passing through dependence the bicrystalline grain boundaries is investigated as a function of misalignment angle. The current decreases as the misalignment angle increases in general. Symmetry-restricted form of transport coefficient tensors is tabulated for multi-dimensional order parameters of the tetragonal and hexagonal systems. A brief discussion of superconducting fluctuations is given in the appendix.

Research Organization:
Wisconsin Univ., Madison, WI (United States)
OSTI ID:
6982303
Country of Publication:
United States
Language:
English