The ICRₙ Value in Intrinsic Josephson Tunnel Junctions in Bi₂Sr₂CaCu₂O8+δ (Bi2212) Mesas


The c-axis current-voltage I(V) characteristics have been obtained on a set of mesas of varying height sculpted on Bi 2Sr 2CaCu 2O 8 + δ (Bi2212) crystals intercalated with HgB 2. The intercalation, along with the small number of junctions in the mesa, N = 6-30, minimizes the degree of self-heating, leading to a consistent Josephson critical current, I C, among junctions in the mesa. The Bi2212 crystals with a bulk T C = 74 K are overdoped and display negligible pseudogap effects allowing an accurate measure of the normal state resistance, R N. These properties make the mesas nearly ideal for the determination of the Josephson I CR N product. We find I CR N values consistently ~30% of the quasiparticle gap parameter, Δ/e, which was measured independently using a mechanical contact, break junction technique. The latter was necessitated by higher bias heating effects in the mesas which prevented direct measurements of the superconducting gap. These values are among the highest reported and may represent the maximum intrinsic value for I CR N. The results indicate that the c-axis transport is a mixture of coherent and incoherent tunneling.



Second Department

Geosciences and Geological and Petroleum Engineering

Keywords and Phrases

Bi-2212; Bias heating; Break junctions; Current voltage; Direct measurement; Gap parameter; Incoherent tunneling; Josephson; Josephson tunnel junctions; Josephson tunneling; Mechanical contact; Normal-state resistance; Overdoped; Pseudo-gap; Quasi particles; Self-heating; Superconducting gaps; Crystals; Current voltage characteristics; Heating; Tunnel junctions

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Article - Journal

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© 2011 Springer New York, All rights reserved.

Publication Date

01 Jan 2011