Probing high-energy electronic excitations in NiO using inelastic neutron scattering

Abstract

High-energy local multiplet excitations of the $d$ electrons are revealed in our inelastic neutron scattering measurements on the prototype magnetic insulator NiO. These become allowed by the presence of both nonzero crystal field and spin-orbit coupling. The observed excitations are consistent with optical, x-ray, and EELS measurements of $d$-$d$ excitations. This experiment serves as a proof of principle that high-energy neutron spectroscopy is a reliable and useful technique for probing electronic excitations in systems with significant crystal-field and spin-orbit interactions.