Robustness of the midgap states predicted to exist on a [l brace]110[r brace] surface of a [ital d][sub [ital x][sup 2][sub [ital a]][minus][ital x][sup 2][sub [ital b]]]-wave superconductor

Journal Article · Thu Dec 01 04:00:00 EST 1994 · Physical Review, B: Condensed Matter; (United States)

DOI:https://doi.org/10.1103/PhysRevB.50.16766· OSTI ID:7056742

Yang, J ^[1]; Hu, C ^[2]

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1. Texas Center for Superconductivity, University of Houston, Houston, Texas 77204 (United States)
2. Texas Center for Superconductivity, University of Houston, Houston, Texas 77204 (United States) Center for Theoretical Physics, Department of Physics, Texas A M University, College Station, Texas 77843-4242 (United States)

It was shown recently that a sizable areal density of midgap states exists on a [l brace]110[r brace] surface of a [ital d][sub [ital x]][sup 2][sub [ital a]][minus][ital x][sup 2][sub [ital b]]-wave superconductor [C.-R. Hu, Phys. Rev. Lett. [bold 72], 1526 (1994)]. Here we study how these midgap states are affected if (i) the surface is not exactly [l brace]110[r brace]; (ii) the crystalline structure is slightly orthorhombic; (iii) and (iv): the order parameter is not a pure [ital d] wave, but is [ital s]+[ital id][sub [ital x]][sup 2][sub [ital a]][minus][ital x][sup 2][sub [ital b]] and [ital d][sub [ital x]][sup 2][sub [ital a]][minus][ital x][sup 2][sub [ital b]]+[ital id][sub [ital x]][sub [ital ax]][sub [ital b]], respectively. We find that for cases (i) and (ii), the midgap surface states still exist but with reduced areal density. For case (iii), all surface-state energies are found to shift away from midgap to [plus minus][vert bar][Delta][sub [ital s]][vert bar]. For case (iv), the surface states exist on both [l brace]110[r brace] and [l brace]100[r brace] surfaces (and on surfaces of all other orientations) but with a [bold k]-dependent energy shift from midgap.

• OSTI ID: 7056742
• Journal Information: Physical Review, B: Condensed Matter; (United States), Journal Name: Physical Review, B: Condensed Matter; (United States) Vol. 50:22; ISSN PRBMDO; ISSN 0163-1829
• Country of Publication: United States
• Language: English

Related Subjects

665411* -- Basic Superconductivity Studies-- (1992-)
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
CRYSTAL STRUCTURE
D WAVES
ENERGY-LEVEL DENSITY
HIGH-TC SUPERCONDUCTORS
ORDER PARAMETERS
PARTIAL WAVES
SUPERCONDUCTORS
SURFACES
WKB APPROXIMATION