Electronic Properties and Superconductivity in Infinite-Layer Nickelate Composts.

In this paper, we investigate the electronic and superconducting properties in nickelate compounds of NiO 2 through perturbative density functional theory (P-DFT) and extended multi-band Bardeen–Cooper–Schrieffer (BCS) theory. We consider four different cases of study: (i) the crystalline structure composed by one layer of NiO 2 , with a central single atom of Nd, Yb or Pr, which is subjected to mechanical compression and tension forces (pressure), (ii) the crystalline structure composed by two layers of NiO 2 with central atom pairs of Nd–Sr, Yb–Sr or Pr–Sr, with level doping x = 0.5 , (iii) the crystalline structure composed by three layers of NiO 2 with a setup of Nd–Nd(Sr)–Nd, Yb–Yb(Sr)–Yb or Pr–Pr(Sr)–Pr (Homogeneous and doping sample), with the level doping x = 0.3 and x = 0.75 and finally (iv) through multi-band theory we study the behavior in a single-layer Nd 1 - x Sr x NiO 2 when x = 0.5 through gaps Δ χ , p , with χ (number of band or orbitals), only with the presence of inter-band coupling V χ χ ′ . As results, for (i), (ii) and (iii) we present the electronic measures of the electronic band structures e-DOS, and density of phonons (mechanical and/or optic) p-DOS. In (i), we show that under pressure there are a redistribution of the band structures for e-DOS and p-DOS, allowing the destruction of Van Hove near Fermi level E F ; thus, in (ii) and (iii) we show the presence of a single flat band when the doping level is x = 0.5 , and for (iv), the inter-band coupling between orbitals plays a key role in the construction of a superconducting phase in nickelate compounds. [ABSTRACT FROM AUTHOR]