Momentum-dependent multiple gaps in magnesium diboride probed by electron tunnelling spectroscopy

Ke Chen; Wenqing Dai; C. G. Zhuang; Qi Li; Steve Carabello; Joseph G. Lambert; Jerome T. Mlack; Roberto C. Ramos; X. X. Xi

doi:10.1038/ncomms1626

Momentum-dependent multiple gaps in magnesium diboride probed by electron tunnelling spectroscopy

Ke Chen, Wenqing Dai, C. G. Zhuang, Qi Li, Steve Carabello, Joseph G. Lambert, Jerome T. Mlack, Roberto C. Ramos, X. X. Xi

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

14 Scopus citations

Abstract

The energy gap is the most fundamental property of a superconductor. MgB₂, a superconductor discovered in 2001, exhibits two different superconducting gaps caused by the different electron-phonon interactions in two weakly interacting bands. Theoretical calculations predict that the gap values should also vary across the Fermi surface sheets of MgB₂. However, until now, no such variation has been observed. It has been suggested that two gap values were sufficient to describe real MgB₂ samples. Here we present an electron tunnelling spectroscopy study on MgB₂/native oxide/Pb tunnel junctions that clearly shows a distribution of gap values, confirming the importance of the anisotropic electron-phonon interaction. The gap values, and their spreads found from the tunnel junction measurements, provide valuable experimental tests for various theoretical approaches to the multi-band superconductivity in MgB₂.

Original language	English (US)
Article number	619
Journal	Nature communications
Volume	3
DOIs	https://doi.org/10.1038/ncomms1626
State	Published - 2012

All Science Journal Classification (ASJC) codes

Chemistry(all)
Biochemistry, Genetics and Molecular Biology(all)
Physics and Astronomy(all)

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title = "Momentum-dependent multiple gaps in magnesium diboride probed by electron tunnelling spectroscopy",

abstract = "The energy gap is the most fundamental property of a superconductor. MgB2, a superconductor discovered in 2001, exhibits two different superconducting gaps caused by the different electron-phonon interactions in two weakly interacting bands. Theoretical calculations predict that the gap values should also vary across the Fermi surface sheets of MgB2. However, until now, no such variation has been observed. It has been suggested that two gap values were sufficient to describe real MgB2 samples. Here we present an electron tunnelling spectroscopy study on MgB2/native oxide/Pb tunnel junctions that clearly shows a distribution of gap values, confirming the importance of the anisotropic electron-phonon interaction. The gap values, and their spreads found from the tunnel junction measurements, provide valuable experimental tests for various theoretical approaches to the multi-band superconductivity in MgB2.",

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AU - Chen, Ke

AU - Dai, Wenqing

AU - Zhuang, C. G.

AU - Li, Qi

AU - Carabello, Steve

AU - Lambert, Joseph G.

AU - Mlack, Jerome T.

AU - Ramos, Roberto C.

AU - Xi, X. X.

PY - 2012

Y1 - 2012

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AB - The energy gap is the most fundamental property of a superconductor. MgB2, a superconductor discovered in 2001, exhibits two different superconducting gaps caused by the different electron-phonon interactions in two weakly interacting bands. Theoretical calculations predict that the gap values should also vary across the Fermi surface sheets of MgB2. However, until now, no such variation has been observed. It has been suggested that two gap values were sufficient to describe real MgB2 samples. Here we present an electron tunnelling spectroscopy study on MgB2/native oxide/Pb tunnel junctions that clearly shows a distribution of gap values, confirming the importance of the anisotropic electron-phonon interaction. The gap values, and their spreads found from the tunnel junction measurements, provide valuable experimental tests for various theoretical approaches to the multi-band superconductivity in MgB2.

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Momentum-dependent multiple gaps in magnesium diboride probed by electron tunnelling spectroscopy

Abstract

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