Break-junction tunneling on MgB2

被引:39
作者
Schmidt, H [1 ]
Zasadzinski, JF
Gray, KE
Hinks, DG
机构
[1] Argonne Natl Lab, Div Mat Sci, Argonne, IL 60439 USA
[2] IIT, Div Phys, Chicago, IL 60616 USA
来源
PHYSICA C-SUPERCONDUCTIVITY AND ITS APPLICATIONS | 2003年 / 385卷 / 1-2期
关键词
break junction; tunneling spectroscopy; multi-gap superconductivity;
D O I
10.1016/S0921-4534(02)02317-1
中图分类号
O59 [应用物理学];
学科分类号
摘要
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, Delta(L) similar to 7.2 meV, close to the expected BCS value, and a small gap, Delta(s) similar to 2.4 meV. The SIS break junctions show clearly that the small gap closes near the bulk critical temperature, T-c = 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 Delta(s) dominates the spectra. In these cases, a subtle feature is observed near Delta(s) + Delta(L) that is reminiscent of strong-coupling effects. This feature is consistent with quasiparticle scattering contributions to the interband coupling which provides an important insight into the nature of two-band superconductivity in MgB2. (C) 2002 Elsevier Science B.V. All rights reserved.
引用
收藏
页码:221 / 232
页数:12
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