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

Monney, Claude; Herzog, Marc; Pulkkinen, Aki; Huang, Y.; Pelliciari, Jonathan; Olalde-Velasco, P.; Katayama, Naoyuk; Nohara, Minoru; Takagi, Hide; Schmitt, Thorsten; Mizokawa, Takashi

doi:10.1103/PhysRevB.102.085148

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Journal article

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
Huang, Y. Swiss Light Source, Photon Science Division, Paul Scherrer Institut, 5232 Villigen PSI, Switzerland - Beijing National Lab for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, P.O. Box 603, 100190 Beijing, China
Pelliciari, Jonathan Swiss Light Source, Photon Science Division, Paul Scherrer Institut, 5232 Villigen PSI, Switzerland - NSLS-II, Brookhaven National Laboratory, Upton, New York 11973, USA
Olalde-Velasco, P. Swiss Light Source, Photon Science Division, Paul Scherrer Institut, 5232 Villigen PSI, Switzerland - Diamond Light Source, Harwell Science and Innovation Campus, Didcot, Oxfordshire OX11 0DE, United Kingdom
Katayama, Naoyuk Department of Applied Physics, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi 464-8603, Japan
Nohara, Minoru Research Institute for Interdisciplinary Science, Okayama University, Okayama 700-8530, Japan
Takagi, Hide Max Planck Institute for Solid State Research, 70569 Stuttgart, Germany - Department of Physics, University of Tokyo, 113-8654 Tokyo, Japan
Schmitt, Thorsten Swiss Light Source, Photon Science Division, Paul Scherrer Institut, 5232 Villigen PSI, Switzerland
Mizokawa, Takashi Department of Applied Physics, Waseda University, Shinjuku, 169-8555 Tokyo, Japan

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

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