Superconducting gap in MgB2:: Electronic Raman scattering measurements of single crystals -: art. no. 087001

Polarization-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 T-c, reaching a maximum Raman shift of 105 +/- 1 cm(-1) [2Delta (0)/k(B)T(c) = 3.96 +/- 0.09] and showing up to 5 cm(-1) anisotropy between polarized and depolarized spectra. The temperature dependence of 2Delta 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.