Electronic Raman scattering of overdoped Tl2Ba2CuO6+delta in high magnetic fields

The excitations across the superconducting gap (2 Delta-peak in B-1g-symmetry Raman spectra) in an overdoped Tl2Ba2CuO6+delta Single crystal have been studied as a function of temperature and field. The 2 Delta-peak intensity, which we interpret as the density of the superconducting condensate around the gap antinodes, is a linear function of temperature, but a nonlinear function of the field. The latter is attributed to renormalization of quasiparticle spectra in the vicinity of vortex lines in the mixed state. The 2 Delta-peak is present above the irreversibility line and yields a conventional temperature dependence of the effective upper critical field.