Electronic structure of a two-dimensional disordered system: Effects of a single impurity with a d(z2) state

Abstract

The spectral properties of a two-dimensional (2D) disordered system are investigated by employing the hybrid Anderson model with s-d(z)2 coupling only between neighboring sites. The local densities of states(LDOS) of the d(z2) and the s orbitals at both the impurity and the neighboring sites are determined by using the recursion method. With increasing s - d(z2) hopping strength, the resonance peak moves toward the band center, and the width of the resonance becomes narrower. The LDOS of the s orbital at the impurity site exhibits a dip at the bare energy of the d(z2) orbital, which can be identified with the Fano anti-resonance. The abrupt variation of the bond order between the s and the d(z2) states is found to be closely correlated with the presence of the anti-resonance. Further, we have analyzed the LDOS of a real disordered system, Cu impurity in an Al host, and have found that the features of a real system can be well understood based on the behavior of the model system.