Effect of atomic geometry on shot noise in aluminum quantum point contacts

We investigate the role of atomic geometry on shot-noise properties of aluminum atomic contacts using first-principles calculations. We study both the effect of atomic separation in the wire as well as the geometry of the contacts. We find that shot noise, as opposed to conductance, is very sensitive to atomic details. In particular, the Fano factor for the asymmetric contact structures is more than double that of the symmetric ones due to increased backscattering, and is within the experimental range. These results indicate that shot noise may be used as a tool to infer the atomic geometries of quantum point contacts.