All MgB2 Josephson Junctions with Amorphous Boron Barriers

Naoki MITAMURA  Chikaze MARUYAMA  Hiroyuki AKAIKE  Akira FUJIMAKI  Rintaro ISHII  Yoshihiro NIIHARA  Michio NAITO  

IEICE TRANSACTIONS on Electronics   Vol.E93-C   No.4   pp.468-472
Publication Date: 2010/04/01
Online ISSN: 1745-1353
DOI: 10.1587/transele.E93.C.468
Print ISSN: 0916-8516
Type of Manuscript: Special Section PAPER (Special Section on Frontiers of Superconductive Electronics)
Category: Junctions
MgB2,  Josephson junction,  amorphous boron,  

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All MgB2 Josephson junctions with amorphous boron barriers have been fabricated on C-plane sapphire substrates by using a co-evaporation method. The junctions showed Josephson currents and the nonlinear current-voltage characteristics which seem to reflect the superconducting energy gap. The critical current was observed when the thickness of the amorphous boron was in the range of 5 nm to 20 nm. The critical current density was estimated to be 0.4 A/cm2 to 450 A/cm2. By observing he temperature dependence of the critical current we found that the junction had a critical temperature of 10 K and a normal layer in its barrier structure.