Transition from <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msub> <mml:mi>s</mml:mi> <mml:mo>±</mml:mo> </mml:msub> </mml:math> -wave to <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msub> <mml:mi>d</mml:mi> <mml:mrow> <mml:msup> <mml:mi>x</mml:mi> <mml:mn>2</mml:mn> </mml:msup> <mml:mo>−</mml:mo> <mml:msup> <mml:mi>y</mml:mi> <mml:mn>2</mml:mn> </mml:msup> </mml:mrow> </mml:msub> </mml:math> -wave superconductivity driven by interlayer interaction in the bilayer two-orbital model of <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:msub> <mml:mtext>La</mml:mtext> <mml:mn>3</mml:mn> </mml:msub> <mml:msub> <mml:mtext>Ni</mml:mtext> <mml:mn>2</mml:mn> </mml:msub> <mml:msub> <mml:mtext>O</mml:mtext> <mml:mn>7</mml:mn> </mml:msub> </mml:mrow> </mml:math>

Abstract

We utilize the fluctuation-exchange approximation on a bilayer two-orbital model, incorporating ${d}_{{x}^{2}\ensuremath{-}{y}^{2}}$ and ${d}_{{z}^{2}}$ orbitals, to explore potential pairing symmetries in the bilayer nickelate ${\mathrm{La}}_{3}{\mathrm{Ni}}_{2}{\mathrm{O}}_{7}$. Our study particularly examines the impact of interlayer Coulomb interactions. In the absence of these interactions, the superconducting gap exhibits ${s}_{\ifmmode\pm\else\textpm\fi{}}$-wave symmetry, with predominant intraorbital pairing in the ${d}_{{z}^{2}}$ orbital. As interlayer interactions increase, ${s}_{\ifmmode\pm\else\textpm\fi{}}$-wave superconductivity is suppressed, while the superconductivity with a ${d}_{{x}^{2}\ensuremath{-}{y}^{2}}$-wave gap is enhanced, resulting in a transition at a critical interaction strength. This ${d}_{{x}^{2}\ensuremath{-}{y}^{2}}$-wave superconductivity is distinct not only from the ${s}_{\ifmmode\pm\else\textpm\fi{}}$-wave superconductivity but also from the intraorbital $d$-wave pairing in cuprate superconductors, as it is dominated by the interlayer pairing between the ${d}_{{x}^{2}\ensuremath{-}{y}^{2}}$ and ${d}_{{z}^{2}}$ orbitals. Additionally, charge fluctuations play a crucial role in driving the transition from ${s}_{\ifmmode\pm\else\textpm\fi{}}$-wave to ${d}_{{x}^{2}\ensuremath{-}{y}^{2}}$-wave superconductivity. Our findings indicate that interlayer Coulomb interactions are crucial for understanding the pairing mechanism in ${\mathrm{La}}_{3}{\mathrm{Ni}}_{2}{\mathrm{O}}_{7}$.

Topics & Concepts