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arXiv · 2306.05121

Electronic correlations and superconducting instability in La$_3$Ni$_2$O$_7$ under high pressure

Frank Lechermann·Jannik Gondolf·Steffen Bötzel·Ilya M. Eremin
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Abstract

Motivated by the report of superconductivity in bilayer La$_3$Ni$_2$O$_7$ at high pressure, we examine the interacting electrons in this system. First-principles many-body theory is utilized to study the normal-state electronic properties. Below 100\,K, a multi-orbital non-Fermi liquid state resulting from loss of Ni-ligand coherence within a flat-band dominated low-energy landscape is uncovered. The incoherent low-temperature Fermi surface displays strong mixing between Ni-$d_{z^2}$ and Ni-$d_{x^2-y^2}$ orbital character. In a model-Hamiltonian picture, spin fluctuations originating mostly from the Ni-$d_{z^2}$ orbital give rise to strong tendencies towards a superconducting instability with $B_{1g}$ or $B_{2g}$ order parameter. The dramatic enhancement of $T_{\rm c}$ in pressurized La$_3$Ni$_2$O$_7$ is due to stronger Ni-$d_{z^2}$ correlations compared to those in the infinite-layer nickelates.

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Frank Lechermann, Jannik Gondolf, Steffen Bötzel, Ilya M. Eremin. 2023-06-08. Electronic correlations and superconducting instability in La$_3$Ni$_2$O$_7$ under high pressure. https://doi.org/10.1103/physrevb.108.l201121

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