Triplet p-wave superconductivity in the low-density extended hubbard model with Coulomb repulsion

Abstract

We analyze superconducting instabilities in 3D and 2D extended Hubbard model with Coulomb repulsion between electrons on neighboring sites in the limit of low electron density (n el → 0) on simple cubic (square) lattice. We show that in a realistic strong-coupling case U ≫ V ≫ W (U and V are the onsite and the intersite Coulomb repulsions, W the bandwidth) the main SC instability corresponds to the p-wave pairing and in the leading order is correctly described by the equations obtained earlier in the absence of the intersite Coulomb interaction V = 0.

Anomalous superconductivity and superfluidity in repulsive fermion systems

“…This model is a natural generalization of the well-known Falikov-Kimball model [71] for systems with a mixed valence; however, it exhibits a richer physics in view of the presence of a finite bandwidth of heavy electrons instead of a localized level. In the Hubbard model with one narrow band, the effective interaction, as it was shown in Refs [69,70,72,73], is determined mainly by the interband Coulomb repulsion of heavy and light electrons U 12 = U HL . The corresponding critical temperature of the superconducting transition depends nonmonotonically on the relative filling of the bands n H /n L and exhibits a wide and clearly pronounced maximum at n H /n L = 4 in the 2D case.…”

“…The coupling between electrons of two bands is achieved by means of the interband Coulomb interaction U 12 n 1 n 2 . As a result, the following exciton-type mechanism of superconductivity becomes possible: the electrons of one band form a Cooper pair via polarization of the electrons of the other band [68][69][70]. In this case, the role of spin polarization is played by the relative filling of two bands n 1 /n 2 .…”

“…We now examine the two-band Hubbard model with one broad band and one narrow band [69,70], which accordingly contains 'heavy' (n 1 = n H ) and 'light' (n 2 = n L ) electrons. This model is a natural generalization of the well-known Falikov-Kimball model [71] for systems with a mixed valence; however, it exhibits a richer physics in view of the presence of a finite bandwidth of heavy electrons instead of a localized level.…”

“…In the so-called unitary limit of the strongly screened Coulomb interaction (f 0 → 1/2) and of the strong electron-polaron effect, m * H /m L ∼ (m H /m L ) 2 . Cor-respondingly, the maximal critical temperature in this case yields [69,70]…”

Anomalous Resistivity and the Electron–Polaron Effect in the Two-Band Hubbard Model with One Narrow Band

“…The two-band model plays an important role both in the physics of conventional multiband s-wave superconductors like Nb [1,2] and in the physics of high-T c materials [3]. It can be useful also for the description of anomalous normal and superconducting properties in different unconventional superconductors such as ruthenates Sr 2 RuO 4 , MgB 2 , new superconductors (SC) based on FeAs layers such as BaFe 2 (As 1-x P x ) 2 [4,5], layered semimetals, dichalcogenites and superlattices, organic superconductors et al [6][7][8]. At the recent conference on stripes and high Tc superconductivity in Rome the fermion-boson multiband SC and Bose-BCS crossover was also analyzed in [9,10].…”