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

Y. Bugoslavsky; Y. Miyoshi; G. K. Perkins; A. V. Berenov; Z. Lockman; J. L. MacManus-Driscoll; L. F. Cohen; A. D. Caplin; H. Y. Zhai; M. P. Paranthaman; H. M. Christen; M. Blamire

doi:10.1088/0953-2048/15/4/308

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

Y. Bugoslavsky, Y. Miyoshi, G. K. Perkins, A. V. Berenov, Z. Lockman, J. L. MacManus-Driscoll, L. F. Cohen, A. D. Caplin, H. Y. Zhai, M. P. Paranthaman, H. M. Christen, M. Blamire

Nanomaterials Chemistry Group

Research output: Contribution to journal › Article › peer-review

44 Scopus citations

Abstract

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 μΩ 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, Δ₁ = 2.3 ± 0.3 meV and Δ₂ = 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.

Original language	English
Pages (from-to)	526-532
Number of pages	7
Journal	Superconductor Science and Technology
Volume	15
Issue number	4
DOIs	https://doi.org/10.1088/0953-2048/15/4/308
State	Published - Apr 2002

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Bugoslavsky, Y., Miyoshi, Y., Perkins, G. K., Berenov, A. V., Lockman, Z., MacManus-Driscoll, J. L., Cohen, L. F., Caplin, A. D., Zhai, H. Y., Paranthaman, M. P., Christen, H. M., & Blamire, M. (2002). Structure of the superconducting gap in MgB₂ from point-contact spectroscopy. Superconductor Science and Technology, 15(4), 526-532. https://doi.org/10.1088/0953-2048/15/4/308

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title = "Structure of the superconducting gap in MgB2 from point-contact spectroscopy",

abstract = "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 Tc of 38.6 ± 0.3 K and resistivity of about 20 μΩ 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, Δ1 = 2.3 ± 0.3 meV and Δ2 = 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 Tc of the film. Possible mechanisms that can explain the intrinsic coexistence of two values of the gap are discussed.",

author = "Y. Bugoslavsky and Y. Miyoshi and Perkins, {G. K.} and Berenov, {A. V.} and Z. Lockman and MacManus-Driscoll, {J. L.} and Cohen, {L. F.} and Caplin, {A. D.} and Zhai, {H. Y.} and Paranthaman, {M. P.} and Christen, {H. M.} and M. Blamire",

year = "2002",

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doi = "10.1088/0953-2048/15/4/308",

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AU - Bugoslavsky, Y.

AU - Miyoshi, Y.

AU - Perkins, G. K.

AU - Berenov, A. V.

AU - Lockman, Z.

AU - MacManus-Driscoll, J. L.

AU - Cohen, L. F.

AU - Caplin, A. D.

AU - Zhai, H. Y.

AU - Paranthaman, M. P.

AU - Christen, H. M.

AU - Blamire, M.

PY - 2002/4

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N2 - 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 Tc of 38.6 ± 0.3 K and resistivity of about 20 μΩ 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, Δ1 = 2.3 ± 0.3 meV and Δ2 = 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 Tc of the film. Possible mechanisms that can explain the intrinsic coexistence of two values of the gap are discussed.

AB - 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 Tc of 38.6 ± 0.3 K and resistivity of about 20 μΩ 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, Δ1 = 2.3 ± 0.3 meV and Δ2 = 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 Tc of the film. Possible mechanisms that can explain the intrinsic coexistence of two values of the gap are discussed.

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VL - 15

SP - 526

EP - 532

JO - Superconductor Science and Technology

JF - Superconductor Science and Technology

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ER -

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

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