# Mapping the unoccupied state dispersions in ${\mathrm{Ta}}_{2}{\mathrm{NiSe}}_{5}$ with resonant inelastic x-ray scattering

• Monney, Claude Département de Physique and Fribourg Center for Nanomaterials, Université de Fribourg, 1700 Fribourg, Switzerland
• Herzog, Marc Institut für Physik und Astronomie, Universität Potsdam, 14476 Potsdam, Germany
• Pulkkinen, Aki Département de Physique and Fribourg Center for Nanomaterials, Université de Fribourg, 1700 Fribourg, Switzerland - School of Engineering Science, LUT University, 53850 Lappeenranta, Finland
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25.08.2020
Published in:
• Physical Review B. - 2020, vol. 102, no. 8, p. 085148
English 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.
Faculty
Faculté des sciences et de médecine
Department
Département de Physique
Language
• English
Classification
Physics
License
License undefined
Identifiers
Persistent URL
https://folia.unifr.ch/unifr/documents/309012
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