Visualizing the unoccupied bulk band structure of topological semimetals with resonant inelastic x-ray scattering.

Recently, the resolving power of resonant inelastic x-ray scattering (RIXS) has been dramatically enhanced, thereby enabling ever more detailed characterization of novel materials. The detection of features of topological origin is of particular interest, especially in settings where other spectroscopies do not perform adequately. Here we will demonstrate how RIXS can be used to infer the unoccupied bulk band structure of topological semimetals, thus enabling us to visualize nodal points above the Fermi level. We model the RIXS cross section using low-energy k.p theories derived from realistic material calculations, such as Weyl semimetals MoTe₂ and TaIrTe₄, which have Weyl nodes in unoccupied bands. Our work promotes high-resolution RIXS as a viable method for the imaging of bulk three-dimensional band structures.