<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msup> <mml:mi>s</mml:mi> <mml:mo>±</mml:mo> </mml:msup> </mml:math> -wave superconductivity in pressurized <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msub> <mml:mi>La</mml:mi> <mml:mn>4</mml:mn> </mml:msub> <mml:msub> <mml:mi>Ni</mml:mi> <mml:mn>3</mml:mn> </mml:msub> <mml:msub> <mml:mi mathvariant="normal">O</mml:mi> <mml:mn>10</mml:mn> </mml:msub> </mml:math>
Ming Zhang, Hongyi Sun, Yubo Liu, Qihang Liu, Wei-Qiang Chen, Fan Yang
Abstract
Recently, evidence of superconductivity (SC) has been reported in pressurized ${\mathrm{La}}_{4}{\mathrm{Ni}}_{3}{\mathrm{O}}_{10}$. Here we study its possible pairing mechanism and pairing symmetry. Through fitting the density-functional-theory band structure, we provide a six-orbital tight-binding model. In comparison with the band structure of ${\mathrm{La}}_{3}{\mathrm{Ni}}_{2}{\mathrm{O}}_{7}$, the additional nonbonding ${d}_{{z}^{2}}$ band is important to the pairing mechanism here. When the multiorbital Hubbard interactions are included, our random-phase-approximation based study yields an ${s}^{\ifmmode\pm\else\textpm\fi{}}$-wave SC. The dominant Fermi-surface nesting with vector ${\mathbf{Q}}_{1}\ensuremath{\approx}(\ensuremath{\pi},\ensuremath{\pi})$ is between the $\ensuremath{\gamma}$ pocket contributed by the bonding ${d}_{{z}^{2}}$ band top and the ${\ensuremath{\alpha}}_{1}$ pocket contributed by the nonbonding ${d}_{{z}^{2}}$ band bottom, leading to the strongest pairing amplitude and opposite gap signs within the two regimes. The dominant real-space pairing is the interlayer ${d}_{{z}^{2}}$-orbital pairing. This ${s}^{\ifmmode\pm\else\textpm\fi{}}$-wave pairing pattern is insensitive to the band details. Upon electron doping, the ${T}_{c}$ would increase promptly before the system enters the N\'eel-ordered spin-density-wave phase.