Pressure-induced trans-proximate correlation in La$_4$Ni$_3$O$_{10}$ and possible routes to enhance its superconductivity

TL;DR

This study uncovers a unique pressure-induced interlayer correlation in La4Ni3O10 superconductors, revealing a potential universal mechanism for superconductivity in nickelates and cuprates, and suggests ways to enhance superconducting properties.

Contribution

It identifies a novel trans-proximate interlayer correlation under pressure and links it to a fractionalization of Ni spin, proposing a new route to improve superconductivity in nickelates.

Findings

Discovery of stronger interlayer correlation than adjacent layers under pressure.

Pressure-induced fractionalization of Ni$^{2+}$ spin from 1 to 1/2.

Correlation resembles cuprate-like electron dynamics, suggesting universal superconducting mechanisms.

Abstract

We report an unexpected trans-proximate interlayer correlation (stronger correlation between disjoint layers than the adjacent ones) in the high-pressure phase of the recently discovered La$_4$Ni$_3$O$_{10}$ superconductors. Accompanied by an unusual pressure-induced fractionalization of Ni$^{2+}$ ionic spin from the standard spin-1 to spin-$\frac{1}{2}$, this trans-proximate correlation results from the emergence of a cross-layer trimer in our multi-energy-scale derivation of the electron dynamics. The resulting low-energy effective description resembles that of the cuprates and suggests a universal superconducting mechanism in all existing nickelate and cuprate superconductors. The rare trans-proximate correlation not only explains the weaker superconductivity in comparison with the related La$_3$Ni$_2$O$_7$ samples, but it also indicates a viable strategy to improve superconductivity in this trilayer nickelate by lowering layer symmetry. Such pressure-induced trans-proximate correlation is expected in many materials and examplifies the engineering of rich uncharted quantum states of matter through pressure.