Kavli Affiliate: Gang Su
| First 5 Authors: Xing-Zhou Qu, Dai-Wei Qu, Jialin Chen, Congjun Wu, Fan Yang
| Summary:
The recently discovered nickelate superconductor La$_3$Ni$_2$O$_7$ has a high
transition temperature near 80 K under pressure, which offers additional
avenues of unconventional superconductivity. Here with state-of-the-art
tensor-network methods, we study a bilayer $t$-$J$-$J_perp$ model for
La$_3$Ni$_2$O$_7$ and find a robust $s$-wave superconductive (SC) order
mediated by interlayer magnetic couplings. Large-scale density matrix
renormalization group calculations find algebraic pairing correlations with
Luttinger parameter of $K_{rm SC} simeq 1$. Infinite projected entangled-pair
state method obtains a nonzero SC order directly in the thermodynamic limit,
and estimates a strong pairing strength $bar{Delta}_z sim mathcal{O}(0.1)$.
Tangent-space tensor renormalization group simulations further determine a high
SC temperature $T_c^*/J sim mathcal{O}(0.1)$ and clarify the temperature
evolution of SC order. Because of the intriguing orbital selective behaviors
and strong Hund’s rule coupling in the compound, $t$-$J$-$J_perp$ model has
strong interlayer spin exchange (while negligible interlayer hopping), which
greatly enhances the SC pairing in the bilayer system. Such a magnetically
mediated strong pairing has also been observed recently in the optical lattice
of ultracold atoms. Our accurate and comprehensive tensor-network calculations
reveal robust SC order in the bilayer $t$-$J$-$J_perp$ model and shed light on
the high-$T_c$ superconductivity in the pressurized nickelate
La$_3$Ni$_2$O$_7$.
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