Cargando…

Manipulation of Stacking Order in Td-WTe(2) by Ultrafast Optical Excitation

[Image: see text] Subtle changes in stacking order of layered transition metal dichalcogenides may have profound influence on the electronic and optical properties. The intriguing electronic properties of Td-WTe(2) can be traced to the break of inversion symmetry resulting from the ground-state stac...

Descripción completa

Detalles Bibliográficos
Autores principales: Ji, Shaozheng, Grånäs, Oscar, Weissenrieder, Jonas
Formato: Online Artículo Texto
Lenguaje:English
Publicado: American Chemical Society 2021
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8291768/
https://www.ncbi.nlm.nih.gov/pubmed/33913693
http://dx.doi.org/10.1021/acsnano.1c01301
_version_ 1783724703661162496
author Ji, Shaozheng
Grånäs, Oscar
Weissenrieder, Jonas
author_facet Ji, Shaozheng
Grånäs, Oscar
Weissenrieder, Jonas
author_sort Ji, Shaozheng
collection PubMed
description [Image: see text] Subtle changes in stacking order of layered transition metal dichalcogenides may have profound influence on the electronic and optical properties. The intriguing electronic properties of Td-WTe(2) can be traced to the break of inversion symmetry resulting from the ground-state stacking sequence. Strategies for perturbation of the stacking order are actively pursued for intentional tuning of material properties, where optical excitation is of specific interest since it holds the potential for integration of ultrafast switches in future device designs. Here we investigate the structural response in Td-WTe(2) following ultrafast photoexcitation by time-resolved electron diffraction. A 0.23 THz shear phonon, involving layer displacement along the b axis, was excited by a 515 nm laser pulse. Pump fluences in excess of a threshold of ∼1 mJ/cm(2) result in formation, with an ∼5 ps time constant, of a new stacking order by layer displacement along the b axis in the direction toward the centrosymmetric 1T* phase. The shear displacement of the layers increases with pump fluence until saturation at ∼8 pm. We demonstrate that the excitation of the shear phonon and the stabilization of the metastable phase are decoupled when using an optical pump as evidenced by observation of a transition also in samples with a pinned shear phonon. The results are compared to dynamic first-principles simulations and the transition is interpreted in terms of a mechanism where transient local disorder is prominent before settling at the atomic positions of the metastable phase. This interpretation is corroborated by results from diffuse scattering. The correlation between excitation of intralayer vibrations and interlayer interaction demonstrates the importance of including both short- and long-range interactions in an accurate description of how optical fields can be employed to manipulate the stacking order in 2-dimensional transition metal dichalcogenides.
format Online
Article
Text
id pubmed-8291768
institution National Center for Biotechnology Information
language English
publishDate 2021
publisher American Chemical Society
record_format MEDLINE/PubMed
spelling pubmed-82917682021-07-21 Manipulation of Stacking Order in Td-WTe(2) by Ultrafast Optical Excitation Ji, Shaozheng Grånäs, Oscar Weissenrieder, Jonas ACS Nano [Image: see text] Subtle changes in stacking order of layered transition metal dichalcogenides may have profound influence on the electronic and optical properties. The intriguing electronic properties of Td-WTe(2) can be traced to the break of inversion symmetry resulting from the ground-state stacking sequence. Strategies for perturbation of the stacking order are actively pursued for intentional tuning of material properties, where optical excitation is of specific interest since it holds the potential for integration of ultrafast switches in future device designs. Here we investigate the structural response in Td-WTe(2) following ultrafast photoexcitation by time-resolved electron diffraction. A 0.23 THz shear phonon, involving layer displacement along the b axis, was excited by a 515 nm laser pulse. Pump fluences in excess of a threshold of ∼1 mJ/cm(2) result in formation, with an ∼5 ps time constant, of a new stacking order by layer displacement along the b axis in the direction toward the centrosymmetric 1T* phase. The shear displacement of the layers increases with pump fluence until saturation at ∼8 pm. We demonstrate that the excitation of the shear phonon and the stabilization of the metastable phase are decoupled when using an optical pump as evidenced by observation of a transition also in samples with a pinned shear phonon. The results are compared to dynamic first-principles simulations and the transition is interpreted in terms of a mechanism where transient local disorder is prominent before settling at the atomic positions of the metastable phase. This interpretation is corroborated by results from diffuse scattering. The correlation between excitation of intralayer vibrations and interlayer interaction demonstrates the importance of including both short- and long-range interactions in an accurate description of how optical fields can be employed to manipulate the stacking order in 2-dimensional transition metal dichalcogenides. American Chemical Society 2021-04-29 2021-05-25 /pmc/articles/PMC8291768/ /pubmed/33913693 http://dx.doi.org/10.1021/acsnano.1c01301 Text en © 2021 The Authors. Published by American Chemical Society Permits the broadest form of re-use including for commercial purposes, provided that author attribution and integrity are maintained (https://creativecommons.org/licenses/by/4.0/).
spellingShingle Ji, Shaozheng
Grånäs, Oscar
Weissenrieder, Jonas
Manipulation of Stacking Order in Td-WTe(2) by Ultrafast Optical Excitation
title Manipulation of Stacking Order in Td-WTe(2) by Ultrafast Optical Excitation
title_full Manipulation of Stacking Order in Td-WTe(2) by Ultrafast Optical Excitation
title_fullStr Manipulation of Stacking Order in Td-WTe(2) by Ultrafast Optical Excitation
title_full_unstemmed Manipulation of Stacking Order in Td-WTe(2) by Ultrafast Optical Excitation
title_short Manipulation of Stacking Order in Td-WTe(2) by Ultrafast Optical Excitation
title_sort manipulation of stacking order in td-wte(2) by ultrafast optical excitation
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8291768/
https://www.ncbi.nlm.nih.gov/pubmed/33913693
http://dx.doi.org/10.1021/acsnano.1c01301
work_keys_str_mv AT jishaozheng manipulationofstackingorderintdwte2byultrafastopticalexcitation
AT granasoscar manipulationofstackingorderintdwte2byultrafastopticalexcitation
AT weissenriederjonas manipulationofstackingorderintdwte2byultrafastopticalexcitation