Data from this instrument will yield comprehensive information about the interaction parameters
specifying the electronic Hamiltonians of 4d-electron materials, unique insight into the spin-orbital
composition of their excited-state wavefunctions, and definitive tests of proposals to realize Kitaev
models with spin-liquid states that are potentially relevant in topological quantum computation. The
element-specificity of RIXS will also allow us to determine the microscopic exchange interactions
in complex materials with both 3d and 4d valence electrons, and its high sensitivity will enable
experiments on operational device structures comprising only a few monolayers. We will thus be able
to tightly integrate momentum-resolved spectroscopy with state-of-the-art, monolayer-by-monolayer
deposition methods of 4d metal-oxide films and heterostructures. The results will fuel a feedback loop
comprising synthesis, characterization, and modeling, which will greatly advance our ability to design
materials and devices whose functionality derives from the collective organization of electrons.