Anisotropic superconductivity: ({ital s}+{ital d})-wave model, ({ital d}+{ital s})-wave model and the effect of normal impurities

Journal Article · Fri Mar 01 04:00:00 EST 1996 · Physical Review, B: Condensed Matter

DOI:https://doi.org/10.1103/PhysRevB.53.5775· OSTI ID:279098

Beal-Monod, M T ^[1]; Maki, K ^[2]

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1. Physique des Solides, Universite de Paris-Sud, 91400 Orsay (France)
2. Department of Physics and Astronomy, University of Southern California, Los Angeles, California 90089-0484 (United States)

We study in three and two dimensions (3D and 2D), some of the superconducting properties of anisotropic hybrid ({ital s}+{ital d})- and ({ital d}+{ital s})-wave superconductor models (depending whether the {ital s} or {ital d} component predominates). The anisotropy is contained in the fermion-fermion pairing interaction as reflecting structural anisotropies of the kind found in layered high-{ital T}{sub {ital c}} cuprates, in particular the orthorhombic ones. We show that even within the weak-coupling formalism and for an isotropic Fermi surface (so that the interaction has a lower symmetry than the Fermi surface), we obtain enhanced values of {Delta}{sub {ital M}}/{ital T}{sub {ital c}} ({Delta}{sub {ital M}} is the maximum value of the gap energy) compared to the BCS one, as well as enhanced {ital T}{sub {ital c}} values. Depending on the anisotropy parameters we can get a four-leaf clover kind of shape for the gap in {bold k} space in 2D, with the size of the leaves in one direction being different from one of those in the perpendicular direction. We also find unusual shapes for the density of states; in particular we can recover the {open_quote}{open_quote}gapless{close_quote}{close_quote} case similar to the one of the purely {ital d}-wave model of the literature. We study two kinds of anisotropic pairings: the first one, in 3D and 2D yields an ({ital s}+{ital d}) pairing; the other one, in 2D, yields a ({ital d}+{ital s}) pairing and is more specifically adapted to orthorhombic high-{ital T}{sub {ital c}} cuprates, the {ital s} component disappearing in the tetragonal case where the distortion is absent and for which the purely {ital d} pairing is recovered. (Abstract Truncated)

• OSTI ID: 279098
• Journal Information: Physical Review, B: Condensed Matter, Journal Name: Physical Review, B: Condensed Matter Journal Issue: 9 Vol. 53; ISSN 0163-1829; ISSN PRBMDO
• Country of Publication: United States
• Language: English

Related Subjects

66 PHYSICS
BCS THEORY
D WAVES
ELECTRON-PHONON COUPLING
HIGH-TC SUPERCONDUCTORS
IMPURITIES
MATHEMATICAL MODELS
PAIRING INTERACTIONS
S WAVES
SUPERCONDUCTIVITY
THREE-DIMENSIONAL CALCULATIONS
TWO-DIMENSIONAL CALCULATIONS