Extended $s$-wave pairing from an emergent Feshbach resonance in bilayer nickelate superconductors

Abstract

Since the discovery of unconventional superconductivity in cuprates, unraveling the pairing mechanism of charge carriers in doped antiferromagnets has been a long-standing challenge. Motivated by the discovery of high-T${}_c$ superconductivity in nickelate bilayer La${}_3$Ni${}_2$O${}_7$ (LNO), we study a minimal mixed dimensional (MixD) $t-J$ model supplemented with a repulsive Coulomb interaction $V$. When hole-doped, previous numerical simulations revealed that the system exhibits strong binding energies, with a phenomenology resembling a BCS-to-BEC crossover accompanied by a Feshbach resonance between two distinct types of charge carriers. Here, we perform a mean-field analysis that enables a direct observation of the BCS-to-BEC crossover as well as microscopic insights into the crossover region and the pairing symmetry for two-dimensional bilayers. We benchmark our mean-field description by comparing it to density-matrix renormalization group (DMRG) simulations in quasi-one dimensional settings and find remarkably good agreement. For the two-dimensional system relevant to LNO our mean-field calculations predict a BCS pairing gap with an extended $s$-wave symmetry, directly resulting from the pairing mechanism's Feshbach-origin. Our analysis hence gives insights into pairing in unconventional superconductors and, further, can be tested in currently available ultracold atom experiments.

14 pages, 7 figures

References in corpus (15)

• Superconductivity near 80 Kelvin in single crystals of La3Ni2O7 under pressure
• High-temperature superconductivity with zero-resistance and strange metal behavior in La${}_3$Ni${}_2$O${}_{7-\delta }$
• Bilayer two-orbital model of La${}_3$Ni${}_2$O${}_7$ under pressure
• Possible $S_{\pm }$-wave superconductivity in La${}_3$Ni${}_2$O${}_7$
• The s${}^{\pm }$-Wave Pairing and the Destructive Role of Apical-Oxygen Deficiencies in La${}_3$Ni${}_2$O${}_7$ Under Pressure
• Possible high $T_c$ Superconductivity in La${}_3$Ni${}_2$O${}_7$ under High Pressure through Manifestation of a Nearly-Half-Filled Bilayer Hubbard Model
• Interlayer Coupling Driven High-Temperature Superconductivity in La${}_3$Ni${}_2$O${}_7$ Under Pressure
• Bilayer $t$-$J$-$J_{\perp }$ Model and Magnetically Mediated Pairing in the Pressurized Nickelate La${}_3$Ni${}_2$O${}_7$
• Antiferromagnetically Driven Electronic Correlation in Iron Pnictides and Cuprates
• Superconducting Instabilities in Strongly-Correlated Infinite-Layer Nickelates
• Strong pairing in mixed dimensional bilayer antiferromagnetic Mott insulators
• Sensitive dependence of pairing symmetry on Ni-$e_g$ crystal field splitting in the nickelate superconductor La${}_3$Ni${}_2$O${}_7$
• Electronic structure, magnetic correlations, and superconducting pairing in the reduced Ruddlesden-Popper bilayer La${}_3$Ni${}_2$O${}_6$ under pressure: different role of $d_{3z^2-r^2}$ orbital compared with La${}_3$Ni${}_2$O${}_7$
• New mechanism and exact theory of superconductivity from strong repulsive interaction
• Feshbach hypothesis of high-Tc superconductivity in cuprates

Cited by in corpus (1)

• Pairing Symmetry Crossover from $d$-wave to $s_{\pm }$-wave in a Bilayer Nickelate Driven by Hund's Coupling and Crystal Field Splitting