High-energy spin excitations in a bilayer nickelate high-Tc superconductor

Very recently, the Ruddlesden-Popper bilayer perovskite La3Ni2O7 has been found to be superconducting under pressure with a Tc of about 80 K [2], representing an exciting advance in finding new unconventional superconductors family. Unlike cuprates and “infinite layer” nickelates, the La3Ni2O7 hosts a bilayer NiO2 square structure with active and orbitals [2,3], with filling fractions and respectively.
Given the presence of AFM interlayer interaction and the half-filling of orbitals, it is anticipated that electrons from different layers will form rung singlets at every site, giving rise to a nearly Mott-localized phase. Importantly, if this scenario is indeed correct, such singlet couplings should manifest even under ambient pressure, as the pressure required to induce superconductivity is relatively modest.
Consequently, we propose a comprehensive study aimed at measuring the high-energy spin excitations of La3Ni2O7, with the objective of detecting potential excitations arising from the formation of spin singlets by electrons. Furthermore, examining the mid-energy spin excitations and determining its in-plane exchange magnetic interactions in single crystal samples will elucidate inconsistencies observed in powder samples measured by neutron and resonant x-ray scattering.