Mapping the unoccupied state dispersions in Ta2NiSe5 with resonant inelastic X-ray scattering

C. Monney, M. Herzog, A. Pulkkinen, Y. Huang, J. Pelliciari, P. Olalde-Velasco, N. Katayama, M. Nohara, H. Takagi, T. Schmitt, T. Mizokawa

Research output: Contribution to journalArticlepeer-review

Abstract

The transition metal chalcogenide Ta2NiSe5 undergoes a second-order phase transition at Tc=328K involving a small lattice distortion. Below Tc, a band gap at the center of its Brillouin zone increases up to about 0.35 eV. In this work, we study the electronic structure of Ta2NiSe5 in its low-temperature semiconducting phase, using resonant inelastic X-ray scattering (RIXS) at the Ni L3 edge. In addition to a weak fluorescence response, we observe a collection of intense Raman-like peaks that we attribute to electron-hole excitations. Using density functional theory calculations of its electronic band structure, we identify the main Raman-like peaks as interband transitions between valence and conduction bands. By performing angle-dependent RIXS measurements, we uncover the dispersion of these electron-hole excitations that allows us to extract the low-energy boundary of the electron-hole continuum. From the dispersion of the valence band measured by angle-resolved photoemission spectroscopy, we derive the effective mass of the lowest unoccupied conduction band.

Original languageEnglish
Article number085148
JournalPhysical Review B
Volume102
Issue number8
DOIs
Publication statusPublished - 2020 Aug 15

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics

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