MgB2 Josephson junctions produced by focused helium ion beam irradiation

Planar magnesium diboride Josephson junctions are fabricated using focused helium ion beam irradiation. A single track of ion irradiation with a 30 kV He+ beam with nominal beam diameter < 0.5 nm is used to create a normal-metal barrier on a MgB2 film deposited by hybrid physical-chemical vapor d...

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Bibliographic Details
Published in:AIP advances 2018-07, Vol.8 (7), p.075020-075020-6
Main Authors: Kasaei, L., Melbourne, T., Manichev, V., Feldman, L. C., Gustafsson, T., Chen, Ke, Xi, X. X., Davidson, B. A.
Format: Article
Language:English
Subjects:
Borides
Chemical vapor deposition
Critical temperature
Helium ions
Ion beams
Ion irradiation
Josephson junctions
Magnesium compounds
Organic chemistry
Physical vapor deposition
Superconducting devices
Temperature dependence
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Summary:Planar magnesium diboride Josephson junctions are fabricated using focused helium ion beam irradiation. A single track of ion irradiation with a 30 kV He+ beam with nominal beam diameter < 0.5 nm is used to create a normal-metal barrier on a MgB2 film deposited by hybrid physical-chemical vapor deposition. Josephson coupling is observed below the critical temperature of the electrodes for a He+ doses between 8x1015/cm2 to 4x1016/cm2. Analysis of the temperature dependence of the normal resistance and critical voltage of the junctions shows highly uniform barriers with nearly ideal resistively-shunted junction behavior for higher-dose junctions, while nonequilibrium effects dominate the properties of lower-dose junctions over most of the temperature range. These results demonstrate that focused helium ion beam irradiation can produce high-quality proximity-coupled MgB2 Josephson junctions with tailorable properties, promising for use in superconducting devices and circuits.
ISSN:2158-3226
2158-3226
DOI:10.1063/1.5030751