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Break-junction tunneling on MgB2
Tunneling data on magnesium diboride, MgB2 are reviewed with a particular focus on superconductor-insulator - superconductor (SIS) junctions formed by a break-junction method. The collective tunneling literature reveals two distinct energy scales, a large gap, *DL ~ 7.2 meV, close to the expected BC...
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Published in: | Physica. C, Superconductivity Superconductivity, 2003-03, Vol.385 (1-2), p.221-232 |
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Main Authors: | , , , |
Format: | Article |
Language: | English |
Citations: | Items that this one cites Items that cite this one |
Online Access: | Get full text |
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Summary: | Tunneling data on magnesium diboride, MgB2 are reviewed with a particular focus on superconductor-insulator - superconductor (SIS) junctions formed by a break-junction method. The collective tunneling literature reveals two distinct energy scales, a large gap, *DL ~ 7.2 meV, close to the expected BCS value, and a small gap, *DS ~ 2.4 meV. The SIS break junctions show clearly that the small gap closes near the bulk critical temperature, Tc = 39 K. The SIS spectra allow proximity effects to be ruled out as the cause for the small gap and therefore make a strong case that MgB2 is a coupled, two-band superconductor. While the break junctions sometimes reveal parallel contributions to the conductance from both bands, it is more often found that *DS dominates the spectra. In these cases, a subtle feature is observed near *DS + *DL that is reminiscent of strong-coupling effects. This feature is consistent with quasiparticle scattering contributions to the interband |
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ISSN: | 0921-4534 |
DOI: | 10.1016/S0921-4534(02)02317-1 |