Evidence for two superconducting gaps in MgB2 |
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Authors: | Chen X K Konstantinovic M J Irwin J C Lawrie D D Franck J P |
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Affiliation: | Department of Physics, Simon Fraser University, Burnaby, British Columbia, Canada V5A 1S6. |
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Abstract: | We have measured the Raman spectra of polycrystalline MgB2 from 25 to 1200 cm(-1). A superconductivity-induced redistribution in the electronic Raman continuum was observed. Two pair-breaking peaks appear in the spectra, suggesting the presence of two superconducting gaps. The measured spectra were analyzed using a quasi-two-dimensional model in which two s-wave superconducting gaps open on two sheets of Fermi surface. For the gap values we have obtained Delta(1) = 22 cm(-1) ( 2.7 meV) and Delta(2) = 50 cm(-1) ( 6.2 meV). Our results suggest that a conventional phonon-mediated pairing mechanism occurs in the planar boron sigma bands and is responsible for the superconductivity of MgB2. |
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