1206.5486 (Grzegorz Litak et al.)

Band filling effects on coherence lengths and penetration depth in the
two-orbital negative-U Hubbard model of superconductivity    [PDF]

Grzegorz Litak, Teet Örd, Küllike Rägo, Artjom Vargunin

The two-orbital superconducting state is modeled by on-site intra-orbital negative-U Hubbard correlations together with inter-orbital pair-transfer interactions. The critical temperature is mainly governed by intra-orbital attractive interactions and it can pass through an additional maximum as a function of band filling. For the certain number of electrons the clear interband proximity effect is observable in the superconducting state of the band with a smaller gap. The influence of band fillings and orbital site energies on the temperature dependencies of two-component superconductivity coherence lengths and magnetic field penetration depth is analyzed. The presence of proximity effect is probably reflected in the relative temperature behaviour of characteristic lengths.

View original: http://arxiv.org/abs/1206.5486