Direct Imaging of Orbitals in Quantum Materials: ground state and excited states

Recently we have developed a new experimental method that can make a direct image of the ground state d-orbitals in transition metal compounds [1,2]. The method, s-core-level x-ray Raman or non-resonant inelastic x-ray scattering (s-NIXS), relies on dipole-forbidden transitions which become available when the experiment is carried out with high momentum transfers. New opportunities are opened up for the investigation of the ground state, especially for quantum materials that are too complex to be handled by ab-initio theories. Here we will go one step further and explore the spectroscopy aspect of s-NIXS in order to study the excited states which are most often dominated by many-body atomic multiplet interactions. We will show that we are able to obtain images by which we can identify the orbital character of those excited states. This in turn facilitates the extraction of important energy parameters in correlated materials.

[1] Yavas et al., Nature Physics 15, 559 (2019)
[2] Leedahl et al., Nature Communications 10, 5447 (2019)