Modeling of tunneling spectroscopy in high-T-c superconductors

The tunneling density of states of high-T-c superconductors is calculated t aking into account the tight-binding band structure, group velocity, and tu nneling directionality for s-wave and d-wave gap symmetry. The characterist ic density of states has asymmetry of the quasiparticle peaks, flat s-wave and cusplike d-wave subgap behavior, and an asymmetric background. It is as sumed that the underlying asymmetry of the conductance peaks is primarily d ue to the features of the quasiparticle energy spectrum and that the d-wave symmetry enhances the degree of asymmetry of the peaks. Increasing the lif etime broadening factor changes the degree of asymmetry of the tunneling co nductance peaks and leads to confluence of the quasiparticle and van Hove s ingularity peaks. (C) 2001 American Institute of Physics.