GINZBURG-LANDAU MODEL OF HEXAGONAL SUPERCONDUCTORS - APPLICATION TO UPT3

We consider the so-called E theory of unconventional hexagonal superconductors in which the superconducting order parameter belongs to one of the two-dimensional E representations of the hexagonal point group. We show that in the presence of a symmetry-breaking field (such as antiferromagnetism in UPt3) there are two distinct mechanisms for obtaining a split transition in zero magnetic field, one of which has been previously discussed. Coupling of the superconductivity to another symmetry-breaking field associated with charge-density-wave modulations is also considered, thus allowing for an interpretation of the observed pressure-temperature phase diagram of UPt3. Also, the anisotropy (or lack of it) of the upper critical field of UPt3 is accounted for, and it is shown that the antiferromagnetic order becomes a canted antiferromagnetic order in the low-temperature superconducting phase for one of the two models presented here. © 1995 The American Physical Society.