Interband scattering at metallic nano-junctions

Interband scattering effect is examined on the electron transport through nano-scale break-junctions of transition metals. Numerical calculations are performed using multi-band tight-binding models. In a model with broad and narrow s bands, the conductance is almost quantized in units of 2e2/h, as in the case of single band. In another model with broad s and narrow p bands, the situation is completely different: the conductance is substantially suppressed by the interband scattering. Based on the calculated results, we suggest a possible mechanism for the conductance quantization in units of e2/h for Ni which has 4s and 3d bands at the Fermi level.