Stability of the coexistent superconducting-nematic phase under the presence of intersite interactions

Abstract

We analyze the effect of intersite interactions on the stability of the coexisting superconducting-nematic phase (SC+N) within the extended Hubbard and t – J – U models on the square lattice. In order to take into account the correlation effects to a proper precision, we use the approach based on the diagrammatic expansion of the Gutzwiller wave function (DE-GWF), which goes beyond the renormalized mean-field theory (RMFT) in a systematic manner. As a starting point of our analysis we discuss the SC+N phase stability as a function of the intrasite Coulomb repulsion and hole doping for the case of the Hubbard model. Next, we show that the exchange interaction term enhances superconductivity while suppresses the nematicity, whereas the intersite Coulomb repulsion acts in the opposite manner. The competing character of the SC and N phases interplay is clearly visible throughout the analysis. A universal conclusion is that the nematic phase does not survive within the t – J – U model for the value of J integral typical for the high- T _C cuprates ( J ≈ 0.1 eV). This result is helpful in providing the understanding of the fundamental role of the nodal direction. For the sake of completeness, the effect of the correlated hopping term is also analyzed. Thus the present discussion contains all relevant two-site interactions which appear in the parametrized single-band model of correlated fermions. At the end, the influence of the higher-order terms of the DE on the rotational symmetry breaking is also shown by comparing the DE-GWF results with those of the RMFT.

Keywords

• high temperature superconductivity
• nematicity
• correlated electron systems
• t–J–U model
• Hubbard model
• Gutzwiller wave function