Spin and charge excitations in optimally doped Bi2Sr2CaCu2O8+delta

We present Raman spectra of low and high-energy charge and spin excitations in Bi2Sr2CaCu2O8-delta single crystals with an optimized critical temperat ure of 95 K. The prominent feature of the high-energy background at around 250 meV is a rearrangement of spectral weight in B-1g and A(1g) + B-2g symm etry below the critical temperature, similar to the observations in underdo ped and optimally doped Y-123 compounds. In the low-energy region, which is influenced by the effects at higher energies, a gap feature in B-1g symmet ry is observed yielding a value for the magnitude of the superconducting or der parameter of Delta = 34 meV. This gap feature is influenced by the orth orhombicity of the crystals and except for a small loss of spectral weight below 25 meV, no gap Feature is visible in A(1g) scattering geometry. (C) 1 998 Elsevier Science Ltd. All rights reserved.