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The charge density wave (CDW) system 1T -TaS2−xSex was investigated using neutron scattering to determine the nature of the in-plane and out-of-plane disorder. From the local structure analysis, it was deduced that the in-plane star of David motifs are distorted with Se doping just like it was previously observed in 1T -TaS2. This is due to random Ta displacements away from the ideal trigonal symmetry regardless of whether the CDW state is commensurate, nearly commensurate, metallic, or insulating. In the chalcogen layer, the atoms are also distorted with displacements in the perpendicular direction to the planes. The chalcogen distortions are most pronounced in TaSSe that superconducts below 3.6 K in comparison to the distortions observed in TaS2 and TaSe2. The implications of the distortions on superconductivity and the effects on the electron pocket proposed to lead to the superconducting state are not understood at present. Unlike in 1T -TaS2 in which both 13c and 3c layer stacking orders were previously reported, in the nearly commensurate metallic state of 1T -TaSSe and the commensurate CDW metallic state of TaSe2, no clear evidence for a stacking order is observed down to 2 K.
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Suppression of Stacking Order with Doping in 1T-TaS2−xSex
In 1T-TaS2−xSex, the charge density wave (CDW) state features a star of David lattice that expands across layers as the system becomes commensurate upon cooling. The layers can also order along the c-axis, and different stacking orders have been proposed. Using neutron scattering on powder samples, we compared the stacking order previously observed in 1T-TaS2 when the system is doped with Se. While at low temperature, a 13c layer sequence stacking was observed in TaS2; this type of ordering was not evident with doping. Doping with Se results in a metallic state in which the Mott transition is suppressed, which may be linked to the absence of layer stacking.
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- Award ID(s):
- 2219493
- PAR ID:
- 10532100
- Publisher / Repository:
- MDPI
- Date Published:
- Journal Name:
- Condensed Matter
- Volume:
- 8
- Issue:
- 4
- ISSN:
- 2410-3896
- Page Range / eLocation ID:
- 89
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript
- Journal Article:
- https://doi.org/10.3390/condmat8040089
