Transport Properties Through Atomic-Size Point Contacts of Multi-Band Metals

We theoretically investigate the effect of the interband scattering on the transport through atomic-size point contacts of multi-band metals. The conductance is evaluated, taking account of the atomic structures by tight-binding models. In the case of single s band, the conductance is almost quantized in units of 2e²/h. In the multi-band model with broad and narrow s bands, the conductance quantization is also observed. With broad s and narrow p bands, on the other hand, the conductance is strongly suppressed with an increase in the interband scattering. This is because the hybridization between s and p orbitals is significantly different in the leads and in the contact region, which forbids the smooth transport of electrons between them.