Impurity Effect of d-wave High-Tc Superconductors in the Presence of the Charge Modulation

Based on a phenomenological model, we study theoretically the impurity effect in d-wave high-Tc superconductors in the presence of the charge-density-wave (CDW) order. Our results verify that the intensity of the resonance state induced by the impurity depends on the CDW scattering strength. It first increases and then decreases as the CDW scattering strength increases. Moreover, the impurity state exist only near the impurity site without the CDW modulation, while it would appear at quite far away from the impurity site in presence of the CDW modulation. The above results may be tested by later scanning tunneling microscopy experiments.