Surface bound states in n-band systems with the quasiclassical approach

We discuss the tunneling spectroscopy at a surface in multiband systems such as Fe-based superconductors with the use of the quasiclassical approach. We extend the single-band method by M. Matsumoto and H. Shiba [J. Phys. Soc. Jpn. 64, 1703 (1995)] into n-band systems (n >= 2). We show that the appearance condition of the zero-bias conductance peak does not depend on details of the pair-potential anisotropy, but it depends on details of the normal-state properties in the case of fully gapped superconductors. The surface density of states in a two-band superconductor is presented as a simplest application. The quasiclassical approach enables us to calculate readily the surface-angular dependence of the tunneling spectroscopy.