Quasiparticle bound states and low-temperature peaks of the conductance of NIS junctions in d-wave superconductors
- P. N. Lebedev Physics Institute, Leninsky Prospect 53, Moscow 117924 (Russia)
- Physikalisches Institut, Universitaet Bayreuth, D-95440 Bayreuth (Germany)
Contributions of quasiparticle states, bound to the boundary of anisotropically paired superconductors, to the density of states and to the conductance of normal-metal{endash}insulator{endash}superconduction (NIS) junctions are studied both analytically and numerically. For smooth surfaces and real order parameters, we find some general results for the bound-state energies. In particular, we show that under fairly general conditions quasiparticle states with nonzero energies exist for momentum directions within a narrow region around the surface normal. The energy dispersion of the bound states always has an extremum for the direction along the normal. Along with the zero-bias anomaly due to midgap states, we find, for quasi-two-dimensional materials, additional low-temperature peaks in the conductance of NIS junctions for voltages determined by the extrema of the bound-state energies. The influence of interface roughness on the conductance is investigated within the framework of Ovchinnikov{close_quote}s model. We show that nonzero-bias peaks at low temperatures may give information on the order parameter in the bulk, even though it is suppressed at the surface. {copyright} {ital 1997} {ital The American Physical Society}
- OSTI ID:
- 530179
- Journal Information:
- Physical Review, B: Condensed Matter, Vol. 55, Issue 22; Other Information: PBD: Jun 1997
- Country of Publication:
- United States
- Language:
- English
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