Temperature and field dependence of MgB2 energy gaps from tunneling spectra

Mohamed H. Badr; K. W. Ng

doi:10.1016/S0921-4534(02)02684-9

Temperature and field dependence of MgB₂ energy gaps from tunneling spectra

Mohamed H. Badr, K. W. Ng

Physics And Astronomy

Research output: Contribution to journal › Conference article › peer-review

Abstract

We have synthesized MgB₂/Pb planar junctions to study the temperature and field dependence of the superconducting energy gap of MgB₂. The major peak occurs at Δ of about 2 meV, and this corresponds to a 2Δ/k_BT_cvalue of 1.18. While this is significantly smaller than the BCS weak coupling value, there are features in the tunneling spectra indicating the possibility of another larger gap. By fitting the dI/dV curves with a simple model, the larger gap is estimated to be about 4.5 times the smaller gap. The temperature dependence of both gaps is BCS-like, and start to open up at temperatures just below T_c (39.5 K). This confirms that these gaps are indeed bulk properties of MgB₂. The junction is stable only up to a field of 3.2 T then "collapsed" into Josephson tunneling for higher fields.

Original language	English
Pages (from-to)	139-140
Number of pages	2
Journal	Physica C: Superconductivity and its Applications
Volume	388-389
DOIs	https://doi.org/10.1016/S0921-4534(02)02684-9
State	Published - May 2003
Event	proceedings of the 23rd international conference on low temper - Hiroshima, Japan Duration: Aug 20 2002 → Aug 27 2002

Bibliographical note

Funding Information:
This work was supported by NSF grant no. DMR9972071. The corresponding author would like to thank the Egyptian Ministry of Higher Education and Scientific Research for supporting this work as well.

Keywords

Energy gap
Josephson effect
MgB
Superconductivity
Tunneling

ASJC Scopus subject areas

Electronic, Optical and Magnetic Materials
Condensed Matter Physics
Energy Engineering and Power Technology
Electrical and Electronic Engineering

Access to Document

10.1016/S0921-4534(02)02684-9

Cite this

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title = "Temperature and field dependence of MgB2 energy gaps from tunneling spectra",

abstract = "We have synthesized MgB2/Pb planar junctions to study the temperature and field dependence of the superconducting energy gap of MgB2. The major peak occurs at Δ of about 2 meV, and this corresponds to a 2Δ/kBTcvalue of 1.18. While this is significantly smaller than the BCS weak coupling value, there are features in the tunneling spectra indicating the possibility of another larger gap. By fitting the dI/dV curves with a simple model, the larger gap is estimated to be about 4.5 times the smaller gap. The temperature dependence of both gaps is BCS-like, and start to open up at temperatures just below Tc (39.5 K). This confirms that these gaps are indeed bulk properties of MgB2. The junction is stable only up to a field of 3.2 T then {"}collapsed{"} into Josephson tunneling for higher fields.",

keywords = "Energy gap, Josephson effect, MgB, Superconductivity, Tunneling",

author = "Badr, {Mohamed H.} and Ng, {K. W.}",

note = "Funding Information: This work was supported by NSF grant no. DMR9972071. The corresponding author would like to thank the Egyptian Ministry of Higher Education and Scientific Research for supporting this work as well.; proceedings of the 23rd international conference on low temper ; Conference date: 20-08-2002 Through 27-08-2002",

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TY - JOUR

T1 - Temperature and field dependence of MgB2 energy gaps from tunneling spectra

AU - Badr, Mohamed H.

AU - Ng, K. W.

N1 - Funding Information: This work was supported by NSF grant no. DMR9972071. The corresponding author would like to thank the Egyptian Ministry of Higher Education and Scientific Research for supporting this work as well.

PY - 2003/5

Y1 - 2003/5

N2 - We have synthesized MgB2/Pb planar junctions to study the temperature and field dependence of the superconducting energy gap of MgB2. The major peak occurs at Δ of about 2 meV, and this corresponds to a 2Δ/kBTcvalue of 1.18. While this is significantly smaller than the BCS weak coupling value, there are features in the tunneling spectra indicating the possibility of another larger gap. By fitting the dI/dV curves with a simple model, the larger gap is estimated to be about 4.5 times the smaller gap. The temperature dependence of both gaps is BCS-like, and start to open up at temperatures just below Tc (39.5 K). This confirms that these gaps are indeed bulk properties of MgB2. The junction is stable only up to a field of 3.2 T then "collapsed" into Josephson tunneling for higher fields.

AB - We have synthesized MgB2/Pb planar junctions to study the temperature and field dependence of the superconducting energy gap of MgB2. The major peak occurs at Δ of about 2 meV, and this corresponds to a 2Δ/kBTcvalue of 1.18. While this is significantly smaller than the BCS weak coupling value, there are features in the tunneling spectra indicating the possibility of another larger gap. By fitting the dI/dV curves with a simple model, the larger gap is estimated to be about 4.5 times the smaller gap. The temperature dependence of both gaps is BCS-like, and start to open up at temperatures just below Tc (39.5 K). This confirms that these gaps are indeed bulk properties of MgB2. The junction is stable only up to a field of 3.2 T then "collapsed" into Josephson tunneling for higher fields.

KW - Energy gap

KW - Josephson effect

KW - MgB

KW - Superconductivity

KW - Tunneling

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