Superconductivity in nickelate and cuprate superconductors with strong bilayer coupling
| Autor: | Fan, Zhen, Zhang, Jian-Feng, Zhan, Bo, Lv, Dingshun, Jiang, Xing-Yu, Normand, Bruce, Xiang, Tao |
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| Rok vydání: | 2023 |
| Předmět: | |
| Zdroj: | Phys. Rev. B 110, 024514 (2024) |
| Druh dokumentu: | Working Paper |
| DOI: | 10.1103/PhysRevB.110.024514 |
| Popis: | The discovery of superconductivity at 80 K under high pressure in La$_3$Ni$_2$O$_7$ presents the groundbreaking confirmation that high-$T_c$ superconductivity is a property of strongly correlated materials beyond cuprates. We use density functional theory (DFT) calculations of the band structure of La$_3$Ni$_2$O$_7$ under pressure to verify that the low-energy bands are composed almost exclusively of Ni 3$d_{x^2-y^2}$ and O 2$p$ orbitals. We deduce that the Ni 3$d_{z^2}$ orbitals are essentially decoupled by the geometry of the high-pressure structure and by the effect of the Ni Hund coupling being strongly suppressed, which results from the enhanced interlayer antiferromagnetic interaction between $d_{z^2}$ orbitals and the strong intralayer hybridization of the $d_{x^2-y^2}$ orbitals with O 2$p$. By introducing a tight-binding model for the Fermi surfaces and low-energy dispersions, we arrive at a bilayer $t$-$t_\perp$-$J$ model with strong interlayer hopping, which we show is a framework unifying La$_3$Ni$_2$O$_7$ with cuprate materials possessing similar band structures, particularly the compounds La$_2$CaCu$_2$O$_6$, Pb$_2$Sr$_2$YCu$_3$O$_8$, and EuSr$_2$Cu$_2$NbO$_8$. We use a renormalized mean-field theory to show that these systems should have ($d$+$is$)-wave superconductivity, with a dominant $d$-wave component and the high $T_c$ driven by the near-optimally doped $\beta$ band, while the $\alpha$ band adds an $s$-wave component that should lead to clear experimental signatures. Comment: 11 pages, 4 figures |
| Databáze: | arXiv |
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