Mottas, M-L;
Jaouen, T;
Hildebrand, B;
Rumo, M;
Vanini, F;
Razzoli, E;
Giannini, E;
... Aebi, P; + view all
(2019)
Semimetal-to-semiconductor transition and charge-density-wave suppression in 1T-TiSe2-xSx single crystals.
Physical Review B
, 99
(15)
, Article 155103. 10.1103/PhysRevB.99.155103.
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Abstract
The transition-metal dichalcogenide 1T -TiSe2 is a quasi-two-dimensional layered material with a phase transition towards a commensurate charge-density wave (CDW) at a critical temperature Tc ≈ 200 K. The relationship between the origin of the CDW instability and the semimetallic or semiconducting character of the normal state, i.e., with the nonreconstructed Fermi-surface topology, remains elusive. By combining angleresolved photoemission spectroscopy (ARPES), scanning tunneling microscopy (STM), and density functional theory (DFT) calculations, we investigate 1T -TiSe2−xSx single crystals. Using STM, we first show that the longrange phase-coherent CDW state is stable against S substitutions with concentrations, at least, up to x = 0.34. The ARPES measurements then reveal a slow but continuous decrease in the overlap between the electron and the hole (e-h) bands of the semimetallic normal state well reproduced by DFT and related to slight reductions of both the CDW order parameter and Tc. Our DFT calculations further predict a semimetal-to-semiconductor transition of the normal state at a higher critical S concentration of xc = 0.9 ± 0.1 that coincides with a suppressed CDW state in TiSeS as measured with STM. Finally, we rationalize the x dependence of the e-h band overlap in terms of isovalent substitution-induced competing chemical pressure and charge localization effects. Our study highlights the key role of the e-h band overlap for the CDW instability.
| Type: | Article |
|---|---|
| Title: | Semimetal-to-semiconductor transition and charge-density-wave suppression in 1T-TiSe2-xSx single crystals |
| Open access status: | An open access version is available from UCL Discovery |
| DOI: | 10.1103/PhysRevB.99.155103 |
| Publisher version: | https://doi.org/10.1103/PhysRevB.99.155103 |
| Language: | English |
| Additional information: | This version is the version of record. For information on re-use, please refer to the publisher’s terms and conditions. |
| UCL classification: | UCL UCL > Provost and Vice Provost Offices > UCL BEAMS UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences > Dept of Physics and Astronomy |
| URI: | https://discovery-pp.ucl.ac.uk/id/eprint/10072604 |
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