Resonant inelastic x-ray scattering from electronic excitations in α−RuCl3 nanolayers

We present Ru ${L}_{3}$-edge resonant inelastic x-ray scattering (RIXS) measurements of spin-orbit and $d\text{\ensuremath{-}}d$ excitations in exfoliated nanolayers of the Kitaev spin-liquid candidate ${\mathrm{RuCl}}_{3}$. Whereas the spin-orbit excitations are independent of thickness, we observe a pronounced redshift and broadening of the $d\text{\ensuremath{-}}d$ excitations in layers with thicknesses below $\ensuremath{\sim}7$ nm. Aided by model calculations, we attribute these effects to distortions of the ${\mathrm{RuCl}}_{6}$ octahedra near the surface. Our study paves the way towards RIXS investigations of electronic excitations in various other two-dimensional materials and heterostructures.