Electronic structure, magnetic correlations, and superconducting pairing in the reduced Ruddlesden-Popper bilayer <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:msub><mml:mi>La</mml:mi><mml:mn>3</mml:mn></mml:msub><mml:msub><mml:mi>Ni</mml:mi><mml:mn>2</mml:mn></mml:msub><mml:msub><mml:mi mathvariant="normal">O</mml:mi><mml:mn>6</mml:mn></mml:msub></mml:mrow></mml:math> under pressure: Different role of <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msub><mml:mi>d</mml:mi><mml:mrow><mml:mn>3</mml:mn><mml:msup><mml:mi>z</mml:mi><mml:mn>2</mml:mn></mml:msup><mml:mo>−</mml:mo><mml:msup><mml:mi>r</mml:mi><mml:mn>2</mml:mn></mml:msup></mml:mrow></mml:msub></mml:math> orbital compared with <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:msub><mml:mi>La</mml:mi><mml:mn>3</mml:mn></mml:msub><mml:msub><mml:mi>Ni</mml:mi><mml:mn>2</mml:mn></mml:msub><mml:msub><mml:mi mathvariant="normal">O</mml:mi><mml:mn>7</mml:mn></mml:msub></mml:mrow></mml:math>
Yang Zhang, Ling-Fang Lin, Adriana Moreo, Thomas Maier, Elbio Dagotto
Abstract
The authors investigate here two bilayer nickelates under pressure, establishing substantial qualitative differences between the two systems. They find that the ${d}_{3{z}^{2}\ensuremath{-}{r}^{2}}$ orbital in La${}_{3}$Ni${}_{2}$O${}_{6}$ and La${}_{3}$Ni${}_{2}$O${}_{7}$ plays a different role: one ``active'' orbital (${d}_{{x}^{2}\ensuremath{-}{y}^{2}})$ vs two ``active'' orbitals (${e}_{g})$, respectively. The Fermi surface only has two sheets in La${}_{3}$Ni${}_{2}$O${}_{6}$, with the $\ensuremath{\gamma}$ pocket absent, different from La${}_{3}$Ni${}_{2}$O${}_{7}$. They also find that La${}_{3}$Ni${}_{2}$O${}_{6}$ is far from a superconducting instability. Moreover, they do not observe changes in the electronic density in La${}_{3}$Ni${}_{2}$O${}_{6}$ under pressure.