Order-parameter symmetries, phase diagrams, and physical properties of two-dimensional unconventional superconductors. I.d-wave-pairing superconductivity

The full set of possible stable states which may arise in two-dimensional superconducting systems, when assuming a d-pairing-wave order parameter, are worked out in the framework of a generalized Landau theory, in which a nontruncated order-parameter expansion is used. The phase diagrams, macroscopic tensors, and gap functions are calculated for three structural symmetries of the normal state: {∞}m, 4mm, and mm2. The superconducting states can be distinguished by their elastic properties, by the orbital paramagnetic or ferromagnetic type order of the condensate, and by their gap functions. A number of recent experimental measurements on the cuprate superconductors are reinterpreted in light of the obtained theoretical results.