Structure of the superconducting gap in MgB2 from point-contact spectroscopy

被引：40
作者：
Bugoslavsky, Y [1 ]
Miyoshi, Y
Perkins, GK
Berenov, AV
Lockman, Z
MacManus-Driscoll, L
Cohen, LF
Caplin, AD
Zhai, HY
Paranthaman, MP
Christen, HM
Blamire, M
机构：
[1] Univ London Imperial Coll Sci Technol & Med, Ctr High Temp Superconduct, London SW7 2BZ, England
[2] Russian Acad Sci, Inst Gen Phys, Moscow 117942, Russia
[3] Oak Ridge Natl Lab, Oak Ridge, TN 37931 USA
[4] Univ Cambridge, Dept Mat Sci, Cambridge CB2 3QZ, England
来源：
SUPERCONDUCTOR SCIENCE & TECHNOLOGY | 2002年 / 15卷 / 04期
关键词：
D O I：
10.1088/0953-2048/15/4/308
中图分类号：
O59 [应用物理学];
学科分类号：
摘要：
We have studied the structure of the superconducting gap in MgB2 thin films by means of point-contact spectroscopy using a gold tip. The films were produced by depositing pure boron on a sapphire substrate, using e-beam evaporation, followed by reaction with magnesium vapour. The films have a T-c of 38.6 +/- 0.3 K and resistivity of about 20 muOmega cm at 40 K. The point-contact spectra prove directly the existence of a multi-valued order parameter in MgB2. with two distinct values of the gap, Delta(1) = 2.3 +/- 0.3 meV and Delta(2) = 6.2 +/- 0.7 meV at 4.2 K. Analysis of the spectra in terms of the Blonder-Tinkham-Klapwijk model reveals that both gaps close simultaneously at the T-c of the film. Possible mechanisms that can explain the intrinsic coexistence of two values of the gap are discussed.
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页码：526 / 532
页数：7
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