NMR evidence for spin fluctuations in the bilayer nickelate La ³Ni²O⁶

We report nuclear magnetic resonance data in the bilayer nickelate La ³Ni²O⁶. This material belongs to a family of low valence nickel oxides with square planar coordination of the Ni ions and is isoelectronic to the high temperature superconducting cuprates. Although the three layer nickelate compound exhibits a spin-state transition accompanied by antiferromagnetic order, the bilayer material shows no phase transition. The NMR data in the bilayer La³Ni²O⁶ reveal the presence of antiferromagnetic spin fluctuations down to 5 K that are surprisingly similar to those present in the magnetically ordered trilayer La⁴Ni³O⁸, suggesting a similar electronic structure in the paramagnetic phase of both compounds.