Mapping the unoccupied state dispersions in Ta$_2$NiSe$_5$ with resonant inelastic x-ray scattering
| Autor: | Monney, C., Herzog, M., Pulkkinen, A., Huang, Y., Pelliciari, J., Olalde-Velasco, P., Katayama, N., Nohara, M., Takagi, H., Schmitt, T., Mizokawa, T. |
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| Rok vydání: | 2020 |
| Předmět: | |
| Druh dokumentu: | Working Paper |
| Popis: | The transition metal chalcogenide Ta$_2$NiSe$_5$ undergoes a second-order phase transition at $T_c=328$ K involving a small lattice distortion. Below $T_c$, 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 Ta$_2$NiSe$_5$ in its low-temperature semiconducting phase, using resonant inelastic x-ray scattering (RIXS) at the Ni $L_3$-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. Comment: accepted for publication in Physical Review B |
| Databáze: | arXiv |
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