Shot noise and Fano factor in tunneling in three-band pseudospin-1 Dirac–Weyl systems

Abstract

Tunneling through a potential barrier of height V0 in a two-dimensional system with a band structure consisting of three bands with a flat band intersecting the touching apices of two Dirac cones is studied. Results of the transmission coefficient at various incident angles, conductivity, shot noise, and Fano factor in this pseudospin-1 Dirac–Weyl system are presented and contrasted with those in graphene which is typical of a pseudospin-1/2 system. The pseudospin-1 system is found to show a higher transmission and suppressed shot noise in general. Significant differences in the shot noise and Fano factor due to the super Klein tunneling effect that allows perfect transmission at all incident angles under certain conditions are illustrated. For Fermi energy EF=V0/2, super Klein tunneling leads to a noiseless conductivity that takes on the maximum value 2e2DkF/(πh) for 0≤EF≤V0. This gives rise to a minimum Fano factor, in sharp contrast with that of a local maximum in graphene. For EF=V0, the band structure of pseudospin-1 system no longer leads to a quantized value of the conductivity as in graphene. Both the conductivity and the shot noise show a minimum with the Fano factor approaching 1/4, which is different from the value of 1/3 in graphene.