The effect of nonmagnetic impurity on the superconducting gap is examined on La2-xSrx(Cu1-yZny)O4 and Y(Ni1-xPtx)2B2C from the T and H dependence of the electronic specific heat Ce(T, H) at low temperatures. In La2-xSrxCuO4, impurity scattering leads to an appearance of a finite density of states (DOS) at the Fermi energy, consistent with d-wave pairing state with nonmagnetic impurity scattering in the unitarity limit. In contrast, nonmagnetic impurity scattering in YNi2B2C leads to a smearing of the gap anisotropy and the opening of a gap in the DOS over the whole Fermi surface, though Ce(T, H) for pure compound suggests the presence of anisotropic gap. This indicates YNi2B2C is a highly anisotropic s-wave superconductor.
ASJC Scopus subject areas
- Condensed Matter Physics