Investigation of the superconducting order parameter in <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><msub><mrow><mi mathvariant="normal">Bi</mi></mrow><mrow><mn>2</mn></mrow></msub></mrow></math><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><msub><mrow><mi mathvariant="normal">Sr</mi></mrow><mrow><mn>2</mn></mrow></msub></mrow></math><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><msub><mrow><mi mathvariant="normal">CaCu</mi></mrow><mrow><mn>2</mn></mrow></msub></mrow></math><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><msub><mrow><mi mathvariant="normal">O</mi></mrow><mrow><mn>8</mn></mrow></msub></mrow></math> single crystals

T. Staufer; R. Nemetschek; R. Hackl; P. Müller; H. Veith

doi:10.1103/PhysRevLett.68.1069

Investigation of the superconducting order parameter in ${Bi}_{2}$ ${Sr}_{2}$ ${CaCu}_{2}$ $O_{8}$ single crystals

T. Staufer, R. Nemetschek, R. Hackl, P. Müller, and H. Veith

Phys. Rev. Lett. 68, 1069 – Published 17 February 1992

Abstract

Single crystals of ${Bi}_{2}$ ${Sr}_{2}$ ${CaCu}_{2}$ $O_{8 + δ}$ with different oxygen concentrations were investigated by Raman scattering. Dependent on the polarizations of the incident and the scattered light, the electronic spectra measured well below $T_{c}$ show either zero or finite intensity at small energy transfers. In oxygen-annealed crystals, the superconducting order parameter Δ is temperature dependent. In contrast, Δ is almost constant in the essentially two-dimensional argon-annealed samples.