https://doi.org/10.1140/epjb/e2008-00072-6
Islands of stability of the d-wave order parameter in s-wave anisotropic superconductors
1
Institute of Physics, Wrocław University of Technology, Wybrzeże Wyspiańskiego 27, 50-370 Wrocław, Poland
2
Department of Physics, Beijing Normal University, Beijing, 100875, P.R. China
3
Faculty of Fundamental Problems of Technology, and Faculty of Computer Science and Management, Wrocław University of Technology, Wybrzeże Wyspiańskiego 27, 50-370 Wrocław, Poland
Corresponding author: a mateusz.krzyzosiak@pwr.wroc.pl
Received:
5
August
2007
Revised:
4
October
2007
Published online:
22
February
2008
In this paper we find and present on diagrams in the coordinates of η=2t1/t0 (the ratio of the second and the first nearest neighbor hopping integrals) and n (the carrier concentration) the areas of stability for the superconducting spin-singlet s- and d-wave and the spin-triplet p-wave order parameters hatching out during the phase transition from the normal to the superconducting phase. The diagrams are obtained for an anisotropic two-dimensional superconducting system with a relatively wide partially-filled conduction band. We study a tight-binding model with an attractive nearest neighbor interaction with the amplitude V1, and the on-site interaction (with the amplitude V0) taken either as repulsive or attractive. The problem of the coexistence of the s-, p- and d-wave order parameters is addressed and solved for chosen values of the ratio V0/V1. A possible island of stability of the d-wave order parameter in the s-wave order parameter environment for a relatively strong on-site interaction is revealed. The triple points, around which the s-, d-, and p-wave order parameters coexist, are localized on diagrams. It is shown that results of the calculations performed for the two-dimensional tight-binding band model are dissimilar with some obtained within the BCS-type approximation.
PACS: 74.20.Rp – Pairing symmetries (other than s-wave) / 74.62.Yb – Other effects
© EDP Sciences, Società Italiana di Fisica, Springer-Verlag, 2008