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The Superconducting Gap in MgB2: Electronic Raman Scattering Measurements of Single Crystals

J. W. Quilty, S. Lee, A. Yamamoto, S. Tajima

cond-mat.supr-conarXiv:cond-mat/0107216

Abstract

Polarisation-resolved Raman scattering measurements were performed on MgB2 single crystals to determine the magnitude, symmetry and temperature dependence of the superconducting gap. A single sharp peak due to Cooper pair breaking appears in the electronic continuum below Tc, reaching an average maximum Raman shift of 105 +/- 1 cm-1 (2 Delta(0) / kBTc = 3.96 +/- 0.09) and showing up to 5 cm-1 anisotropy between polarised and depolarised spectra. The temperature dependence of 2 Delta follows that predicted from BCS theory, while the anisotropy decreases with decreasing temperature. It is concluded that the Raman results are consistent with a slightly anisotropic s-wave gap in a conventional BCS superconductor.

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