Energy gap from tunneling and metallic contacts onto MgB2:: Possible evidence for a weakened surface layer -: art. no. 220504

被引:106
作者
Schmidt, H
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
关键词
D O I
10.1103/PhysRevB.63.220504
中图分类号
T [工业技术];
学科分类号
08 ;
摘要
Point-contact tunnel junctions using a Au tip on sintered MgB2 pellets reveal a sharp superconducting energy gap that is confirmed by subsequent metallic contacts made on the same sample. The peak in the tunneling conductance and the metallic contact conductance follow the BCS form, but the gap values of 4.3 -4.6 meV are less than the weak-coupling BCS value of 5.9 meV for the bulk T-c of 39 K. The low value of Delta compared to the BCS value for the bulk T-c is possibly due to chemical reactions at the surface.
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页数:4
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