Collective properties of superconductors with nontrivial pairing

Abstract

Three-and two-dimensional models of p-and d-pairing are constructed for superconductors and superfluid quantum liquids using the functional integration formalism. In these models, the collective excitation spectra are calculated for superconductors with nontrivial pairing (such as high-temperature superconductors (HTSC) and heavy-fermion superconductors (HFSC)) for p-and d-pairing. Both three-and two-dimensional systems are considered. Some of recent ideas concerning the realization of the mixture of different states in HTSC are considered. In particular, the mixture of states \(d_{x^2 - y^2 } + id_{xy} \) is analyzed. The obtained results of calculations of collective excitation spectra in superconductors with nontrivial pairing may be used for determining the type of pairing and the order parameter in HTSC and HFSC and also for interpreting the experimental results on ultrasound and microwave absorption in these system.