Manifestations of Symmetry and Internal Phases in Unconventional Superconductors
Abstract
A study of unconventional superconductivity is presented. The general GinzburgLandau approach based on the broken symmetry is reviewed. By introducing the coupling between the antiferromagnetic and superconducting ordering which belongs to the ^1E _{rm g} representation of the D_{rm 4h} group, we obtain nine possible phase diagrams of the heavy fermion superconductor URu_2Si _2 in the HT plane. The domain wall formed by two time reversed states of the mixture order parameter belonging to A_{rm 1g} +/ iB_{rm 1g} representation of the tetragonal group results in a weak superconducting region which acts as a barrier 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 the bicrystalline grain boundaries is investigated as a function of misalignment angle. The current decreases as the misalignment angle increases in general. Symmetryrestricted form of transport coefficient tensors is tabulated for multidimensional order parameters of the tetragonal and hexagonal systems. A brief discussion of superconducting fluctuations is given in the appendix.
 Publication:

Ph.D. Thesis
 Pub Date:
 1992
 Bibcode:
 1992PhDT.......152B
 Keywords:

 HIGH TEMPERATURE SUPERCONDUCTORS;
 Physics: Condensed Matter