Superconductivity in infinite-layer nickelates: Role of <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mi>f</mml:mi></mml:math> orbitals

Abstract

Employing first-principles density functional theory calculations and Wannierization of the low-energy band structure, we analyze the electronic structure of undoped, infinite-layer nickelate compounds ${\mathrm{NdNiO}}_{2},$ ${\mathrm{PrNiO}}_{2},$ and ${\mathrm{LaNiO}}_{2}$. Our study reveals the important role of the nonzero $f$-ness of Nd and Pr atoms, as opposed to the ${f}^{0}$ occupancy of La. The nonzero $f$-ness becomes effective in lowering the energy of the rare-earth $5d$ hybridized axial orbital, thereby enhancing the electron pockets and influencing the Fermi surface topology. The Fermi surface topology of ${\mathrm{NdNiO}}_{2}$ and ${\mathrm{PrNiO}}_{2}$ is strikingly similar, while differences are observed for ${\mathrm{LaNiO}}_{2}$. This difference shows up in computed doping-dependent superconducting properties of the three compounds within a weak coupling theory, which finds two-gap superconductivity for ${\mathrm{NdNiO}}_{2}$ and ${\mathrm{PrNiO}}_{2}$, and the possibility of a single-gap superconductivity for ${\mathrm{LaNiO}}_{2}$ with the strength of superconductivity suppressed by almost a factor of 2, compared to the Nd or Pr compound.