Strong pairing and symmetric pseudogap metal in a double Kondo lattice model: From a nickelate superconductor to a tetralayer optical lattice

Abstract

In this work, we propose and study a double Kondo lattice model which hosts robust superconductivity. The system consists of two identical Kondo lattice models in two separate layers, with Kondo coupling JK within each layer, while the localized spin moments are coupled together via an interlayer on-site antiferromagnetic spin coupling J⊥. We consider the strong J⊥ limit, wherein the local moments tend to form rung singlets and are thus gapped. However, the Kondo coupling JK transmits the interlayer entanglement between the local moments to the itinerant electrons. Consequently, the itinerant electrons experience a strong interlayer antiferromangetic spin coupling and form strong interlayer pairing, which is confirmed through numerical simulation in one dimensional system. Experimentally, the JK→−∞ limits of the model describes the recently found bilayer nickelate La3Ni2O7, while the JK>0 side can be realized in tetralayer optical lattice of cold atoms. Two extreme limits, JK→−∞ and JK→+∞ limit are shown to be simplified to a bilayer type II t-J model and a bilayer one-orbital t-J model, respectively. Thus, our double Kondo lattice model offers a unified framework for nickelate superconductor and tetralayer optical lattice quantum simulator upon changing the sign of JK. We highlight both the qualitative similarity and the quantitative difference in the two sides of JK. Finally, we discuss the possibility of a symmetric Kondo breakdown transition in the model with a symmetric pseudogap metal corresponding to the usual heavy Fermi liquid.

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