Resonant inelastic X-ray scattering in the topological semimetal FeSi

Abstract

The energy spectrum of topological semimetals contains protected degeneracies in reciprocal space that correspond to Weyl, Dirac, or multifold fermionic states. To exploit the unconventional properties of these states, one has to access the electronic structure of the three-dimensional bulk. In this work, we present the first joint theory-experiment study of the electronic structure of a candidate topological semimetal with resonant inelastic X-ray scattering (RIXS). We resolve the bulk electronic states of FeSi using momentum-dependent RIXS at the Fe $L_3$ edge. We observe a broad excitation continuum devoid of sharp features, consistent with particle-hole scattering in an underlying electronic band structure. Using density functional theory (DFT), we calculate the electronic structure of FeSi and derive a band theory formulation of RIXS in the fast collision approximation to model the scattering process with zero adjustable parameters. While band theory predicts an excitation continuum with broad spectral features similar to the observed ones, discrepancies between theory and experiment suggest the presence of low-energy processes that DFT alone does not account for. This first study of RIXS in a topological semimetal shows that RIXS is a useful tool for revealing unanticipated behavior of bulk electronic states in this class of materials.

arXiv commentv2: published version

References in corpus (34)

• Topological Insulators
• Maximally-localized generalized Wannier functions for composite energy bands
• Weyl and Dirac Semimetals in Three Dimensional Solids
• Resonant Inelastic X-ray Scattering Studies of Elementary Excitations
• Beyond Dirac and Weyl fermions: Unconventional quasiparticles in conventional crystals
• Observation of Weyl nodes in TaAs
• Signatures of the Adler-Bell-Jackiw chiral anomaly in a Weyl Fermion semimetal
• Topological Semimetals
• Three-Dimensional Topological Insulators
• Bulk Topological Invariants in Noninteracting Point Group Symmetric Insulators
• Multiple types of topological fermions in transition metal silicides
• Topological Nature of Anomalous Hall Effect in Ferromagnet
• Observation of Double Weyl Phonons in Parity-Breaking FeSi
• Theory of Resonant Inelastic X-ray Scattering by Collective Magnetic Excitations
• Signatures of electronic correlations in iron silicide
• Bulk Band Gaps in Divalent Hexaborides
• High-temperature charge density wave correlations in La${}_{1.875}$Ba${}_{0.125}$CuO${}_4$ without spin-charge locking
• Insights into the High Temperature Superconducting Cuprates from Resonant Inelastic X-ray Scattering
• Symmetry analysis of magneto-optical effects: The case of x-ray diffraction and x-ray absorption at the transition metal L23 edge
• Resonant Inelastic X-ray Scattering on Spin-Orbit Coupled Insulating Iridates
• LDA+DMFT approach to resonant inelastic x-ray scattering in correlated materials
• EDRIXS: An open source toolkit for simulating spectra of resonant inelastic x-ray scattering
• Exploring Quantum Materials with Resonant Inelastic X-Ray Scattering
• Resonant inelastic x-ray scattering operators for $t_{2g}$ orbital systems
• Femtosecond dynamics of magnetic excitations from resonant inelastic x-ray scattering in CaCu2O3
• Electronic Structure Studies of FeSi: A Chiral Topological System
• Tuning spin excitations in magnetic films by confinement
• Role of Oxygen States in the Low Valence Nickelate La${}_4$Ni${}_3$O${}_8$
• Resonant inelastic x-ray scattering as a probe of band structure effects in cuprates
• Bulk spectroscopic measurement of the topological charge of Weyl nodes with resonant x-rays
• Band structure effects in nitrogen K-edge resonant inelastic X ray scattering from GaN
• Probing magnetic orbitals and Berry curvature with circular dichroism in resonant inelastic X-ray scattering
• Resonant inelastic x-ray scattering (RIXS) spectra of magnesium diboride
• Interplay of broken symmetry and delocalized excitations in the insulating state of 1$T$-TaS${}_2$