Effect of kz variation of da2-b2-wave order parameter on c-axis tunneling spectroscopy

The effect of kz variation of the superconducting da2-b2-wave order parameter on c-axis tunneling spectra of metal-superconductor junctions is theoretically investigated. In the high transmission limit, the variation does not cause obvious changes in the shape of the conductance spectrum, while in the tunneling limit the effect is more apparent. The coherence peak of the conductance spectrum gets wider as the variation of the order parameter is larger. The effect of the variation can be seen more clearly in the spectrum of the derivative of the conductance in both limits.