Current-voltage relation for asymmetric ballistic superconducting junctions

Journal Article · Sun Sep 01 00:00:00 EDT 1996 · Physical Review, B: Condensed Matter

DOI:https://doi.org/10.1103/PhysRevB.54.6557· OSTI ID:383254

Hurd, M; Datta, S; Bagwell, P F ^[1]

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1. Purdue University, School of Electrical and Computer Engineering, West Lafayette, Indiana 47907 (United States)

We calculate the dc current-voltage ({ital I}-{ital V}) relation for a ballistic superconductor{endash}normal metal{endash}superconductor ({ital S}{sub 1}{ital NS}{sub 2}) junction, where the two superconducting contacts have different energy gaps ({Delta}{sub 2}{ge}{Delta}{sub 1}{ge}0). Several new features appear in the {ital I}-{ital V} relation as it evolves from a {ital NS} junction ({Delta}{sub 1}=0) to the symmetric {ital SNS} junction ({Delta}{sub 1}={Delta}{sub 2}). The dc current {ital I}{sub 0} flowing at small voltages is {ital I}{sub 0}=4{ital e}{Delta}{sub 1}/{ital h}, and is different from the critical current {ital I}{sub {ital c}}. The differential conductance changes abruptly at {ital eV}={Delta}{sub 2}{minus}{Delta}{sub 1} due to the loss of a single Andreev reflection from the larger-gap superconductor. Finally, the voltages {ital V}{sub {ital n}} at which subharmonic gap structures appear in the {ital I}-{ital V} relation for temperatures {ital k}{sub {ital B}}{ital T}{approx_equal}{Delta}{sub 2} depend on both energy gaps {Delta}{sub 1} and {Delta}{sub 2}. We find a systematic way to classify this subgap structure. {copyright} {ital 1996 The American Physical Society.}

• OSTI ID: 383254
• Journal Information: Physical Review, B: Condensed Matter, Vol. 54, Issue 9; Other Information: PBD: Sep 1996
• Country of Publication: United States
• Language: English

Related Subjects

66 PHYSICS
SUPERCONDUCTING JUNCTIONS
ELECTRICAL PROPERTIES
QUASI PARTICLES
ENERGY GAP
CRITICAL CURRENT
ORDER PARAMETERS
TEMPERATURE DEPENDENCE
IV CHARACTERISTIC