NMR evidence for antiferromagnetic order in a planar 3d9/3d8 nickelate

TL;DR

This study uses La-139 NMR to demonstrate antiferromagnetic order in La4Ni3O8, a nickelate with a 3d9/3d8 electronic configuration, revealing its potential as a cuprate analog for high-temperature superconductivity.

Contribution

First NMR evidence of antiferromagnetic order in La4Ni3O8, highlighting its similarities to cuprate parent compounds and its unique electronic structure.

Findings

Antiferromagnetic order observed below 105 K.

Spectral changes indicate low energy antiferromagnetic correlations.

La4Ni3O8's electronic structure resembles cuprate parent compounds.

Abstract

We report La-139 Nuclear Magnetic Resonance (NMR) data in La4Ni3O8 which reveals the presence of antiferromagnetic order below T_N ~ 105 K. This compound contains two-dimensional layers of NiO2 that are isostructural to the copper oxide planes of the high temperature superconductors. This compound is remarkable because the average Ni valence of 1.33+ for formally 2Ni1+ + Ni2+ indicates a 3d9/3d8 electronic configuration. Nickel oxides with Ni1+ valence are rare and unstable, yet may provide new routes to high temperature superconductivity. La4Ni3O8, with antiferromagnetic order of S=1/2 Ni1+ spins, is analogous to the parent compounds of the cuprate superconductors. Our data clearly reveal dramatic spectral changes and low energy antiferromagnetic correlations associated with the onset of long range order below T_N.