Optomechanical resonators based on transition metal dichalcogenide monolayers

Suspended monolayer transition metal dichalcogenides (TMD) aremembranes that combine ultralow mass and exceptional optical prop-erties, making them intriguing materials for opto-mechanical applica-tions. However, the low measured quality factor of TMD resonatorshas been a roadblock so far. In this t...

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Autor: Morell Bennasser, Nicolás
Tipo de recurso: tesis doctoral
Fecha de publicación:2018
País:España
Institución:Universitat Politècnica de Catalunya (UPC)
Repositorio:UPCommons. Portal del coneixement obert de la UPC
Idioma:inglés
OAI Identifier:oai:upcommons.upc.edu:2117/127498
Acceso en línea:https://hdl.handle.net/2117/127498
https://dx.doi.org/10.5821/dissertation-2117-127498
Access Level:acceso abierto
Palabra clave:Àrees temàtiques de la UPC::Física
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repository_id_str
dc.title.none.fl_str_mv Optomechanical resonators based on transition metal dichalcogenide monolayers
title Optomechanical resonators based on transition metal dichalcogenide monolayers
spellingShingle Optomechanical resonators based on transition metal dichalcogenide monolayers
Morell Bennasser, Nicolás
Àrees temàtiques de la UPC::Física
title_short Optomechanical resonators based on transition metal dichalcogenide monolayers
title_full Optomechanical resonators based on transition metal dichalcogenide monolayers
title_fullStr Optomechanical resonators based on transition metal dichalcogenide monolayers
title_full_unstemmed Optomechanical resonators based on transition metal dichalcogenide monolayers
title_sort Optomechanical resonators based on transition metal dichalcogenide monolayers
dc.creator.none.fl_str_mv Morell Bennasser, Nicolás
author Morell Bennasser, Nicolás
author_facet Morell Bennasser, Nicolás
author_role author
dc.contributor.none.fl_str_mv Bachtold, Adrian
dc.subject.none.fl_str_mv Àrees temàtiques de la UPC::Física
topic Àrees temàtiques de la UPC::Física
description Suspended monolayer transition metal dichalcogenides (TMD) aremembranes that combine ultralow mass and exceptional optical prop-erties, making them intriguing materials for opto-mechanical applica-tions. However, the low measured quality factor of TMD resonatorshas been a roadblock so far. In this thesis, we first show an ultra-sensitive optical readout of monolayer TMD resonators that allows usto reveal their mechanical properties at cryogenic temperatures. Wefind that the quality factor of monolayer WSe2resonators greatly in-creases below room temperature, reaching values as high as 16000 at liquid nitrogen temperature and 47000 at liquid helium temper-ature. This surpasses the quality factor of monolayer graphene res-onators with similar surface areas. Upon cooling the resonator, the res-onant frequency increases significantly due to the thermal contractionof the WSe2lattice. These measurements allow us to experimentallystudy the thermal expansion coefficient of WSe2 monolayers for thefirst time. High Q-factors are also found in resonators based on MoS2 and MoSe2 monolayers. The high quality-factor found in this workopens new possibilities for coupling mechanical vibrational states totwo-dimensional excitons, valley pseudospins, and single quantumemitters and for quantum opto-mechanical experiments based on theCasimir interaction.The sensing capabilities offered by these high Q-factor nanome-chanical oscillators are also of interest for studying thermodynamicproperties in condensed matter regimes that are difficult to access. Inthe second part of the thesis, we use optomechanical systems basedon a MoSe2 monolayer to probe the thermal properties of phononsin two-dimensional lattices. We measure the thermal conductivityand the specific heat capacity down to cryogenic temperature. Thephonon transport crossovers from the diffusive to the ballistic regimewhen lowering the temperature below~100 K. The temperature de-pendence of the specific heat capacity approaches a quadratic depen-dence, the signature of two-dimensional lattices. Both the thermalconductivity and the specific heat capacity measurements are consis-tent with predictions based on first-principles. Our result establishes anew strategy to investigate thermal transport in two-dimensional ma-terials, and allows for exploring the phonon hydrodynamic regime,the anomalous heat conduction, and the phase transitions of electronicmany-body collective phenomena in monolayers
publishDate 2018
dc.date.none.fl_str_mv 2018
2018-12-17
2019
2019-01-23
dc.type.none.fl_str_mv doctoral thesis
http://purl.org/coar/resource_type/c_db06
VoR
http://purl.org/coar/version/c_970fb48d4fbd8a85
dc.type.openaire.fl_str_mv info:eu-repo/semantics/doctoralThesis
format doctoralThesis
dc.identifier.none.fl_str_mv https://hdl.handle.net/2117/127498
https://dx.doi.org/10.5821/dissertation-2117-127498
url https://hdl.handle.net/2117/127498
https://dx.doi.org/10.5821/dissertation-2117-127498
dc.language.none.fl_str_mv Inglés
eng
language_invalid_str_mv Inglés
language eng
dc.rights.none.fl_str_mv open access
http://purl.org/coar/access_right/c_abf2

http://creativecommons.org/licenses/by-nc-sa/4.0/
dc.rights.openaire.fl_str_mv info:eu-repo/semantics/openAccess
rights_invalid_str_mv open access
http://purl.org/coar/access_right/c_abf2

http://creativecommons.org/licenses/by-nc-sa/4.0/
eu_rights_str_mv openAccess
dc.format.none.fl_str_mv application/pdf
dc.publisher.none.fl_str_mv Universitat Politècnica de Catalunya
publisher.none.fl_str_mv Universitat Politècnica de Catalunya
dc.source.none.fl_str_mv reponame:UPCommons. Portal del coneixement obert de la UPC
instname:Universitat Politècnica de Catalunya (UPC)
instname_str Universitat Politècnica de Catalunya (UPC)
reponame_str UPCommons. Portal del coneixement obert de la UPC
collection UPCommons. Portal del coneixement obert de la UPC
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repository.mail.fl_str_mv
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spelling Optomechanical resonators based on transition metal dichalcogenide monolayersMorell Bennasser, NicolásÀrees temàtiques de la UPC::FísicaSuspended monolayer transition metal dichalcogenides (TMD) aremembranes that combine ultralow mass and exceptional optical prop-erties, making them intriguing materials for opto-mechanical applica-tions. However, the low measured quality factor of TMD resonatorshas been a roadblock so far. In this thesis, we first show an ultra-sensitive optical readout of monolayer TMD resonators that allows usto reveal their mechanical properties at cryogenic temperatures. Wefind that the quality factor of monolayer WSe2resonators greatly in-creases below room temperature, reaching values as high as 16000 at liquid nitrogen temperature and 47000 at liquid helium temper-ature. This surpasses the quality factor of monolayer graphene res-onators with similar surface areas. Upon cooling the resonator, the res-onant frequency increases significantly due to the thermal contractionof the WSe2lattice. These measurements allow us to experimentallystudy the thermal expansion coefficient of WSe2 monolayers for thefirst time. High Q-factors are also found in resonators based on MoS2 and MoSe2 monolayers. The high quality-factor found in this workopens new possibilities for coupling mechanical vibrational states totwo-dimensional excitons, valley pseudospins, and single quantumemitters and for quantum opto-mechanical experiments based on theCasimir interaction.The sensing capabilities offered by these high Q-factor nanome-chanical oscillators are also of interest for studying thermodynamicproperties in condensed matter regimes that are difficult to access. Inthe second part of the thesis, we use optomechanical systems basedon a MoSe2 monolayer to probe the thermal properties of phononsin two-dimensional lattices. We measure the thermal conductivityand the specific heat capacity down to cryogenic temperature. Thephonon transport crossovers from the diffusive to the ballistic regimewhen lowering the temperature below~100 K. The temperature de-pendence of the specific heat capacity approaches a quadratic depen-dence, the signature of two-dimensional lattices. Both the thermalconductivity and the specific heat capacity measurements are consis-tent with predictions based on first-principles. Our result establishes anew strategy to investigate thermal transport in two-dimensional ma-terials, and allows for exploring the phonon hydrodynamic regime,the anomalous heat conduction, and the phase transitions of electronicmany-body collective phenomena in monolayersLos dicalcogenuros de metal de transición (TMD) monocapa suspendidos combinan una masa ultrabaja y propiedades ópticas excepcionales, lo que los convierte en materiales intrigantes para aplicaciones opto-mecánicas. Sin embargo, el bajo factor de calidad Q medido en los resonadores de TMD ha sido un obstáculo hasta ahora. En esta tesis, primero mostramos una lectura óptica ultra sensible de resonadores TMD de monocapa que nos permite revelar sus propiedades mecánicas a temperaturas criogénicas. Encontramos que el factor de calidad de los resonadores WSe2 monocapa aumenta considerablemente por debajo de la temperatura ambiente, alcanzando valores tan altos como 1.6 x 104 en temperatura de nitrógeno líquido y 4.7 x 104 en temperatura de helio líquido. Esto supera el factor de calidad de los resonadores de grafeno monocapa con áreas de superficie similares. Al enfriar el resonador, la frecuencia de resonancia aumenta significativamente debido a la contracción térmica la red del cristal de WSe2. Estas mediciones nos permiten estudiar experimentalmente el coeficiente de expansión térmica de las monocapas de WSe2 por primera vez. Los altos factores Q también se encuentran en los resonadores basados en las monocapas de MoS2 y MoSe2. El alto factor de calidad que se encuentra en este trabajo abre nuevas posibilidades para acoplar estados vibracionales mecánicos a excitones bidimensionales, valley pseudo-spins y emisores cuánticos únicos y para experimentos opto-mecánicos cuánticos basados en la interacción de Casimir. Las capacidades de detección ofrecidas por este nano-resonador mecánico de alto factor Q también son interesantes para estudiar propiedades termodinámicas en regímenes de la materia condensada a los que es difícil acceder. En la segunda parte de la tesis, utilizamos sistemas optomecánicos basados en una monocapa de MoSe2 para probar las propiedades térmicas de los fonones en redes de cristales bidimensionales. Medimos la conductividad térmica y la capacidad calorífica específica hasta temperaturas criogénicas. Los régimenes de transporte de fonones pasan de el difuso al balístico al bajar la temperatura por debajo de 100 K. La dependencia de la temperatura de la capacidad calorífica específica se aproxima a una dependencia cuadrática, lo cual es la firma de las redes bidimensionales. Tanto la conductividad térmica como las mediciones de la capacidad calorífica específica son coherentes con las predicciones basadas en primeros principios. Nuestro resultado establece una nueva estrategia para investigar el transporte térmico en materiales bidimensionales y permite explorar el régimen hidrodinámico de fonones, la conducción de calor anómala y las transiciones de fase de los fenómenos colectivos de cuerpos electrónicos en monocapas.Universitat Politècnica de CatalunyaBachtold, Adrian20182018-12-1720192019-01-23doctoral thesishttp://purl.org/coar/resource_type/c_db06VoRhttp://purl.org/coar/version/c_970fb48d4fbd8a85info:eu-repo/semantics/doctoralThesisapplication/pdfhttps://hdl.handle.net/2117/127498https://dx.doi.org/10.5821/dissertation-2117-127498reponame:UPCommons. Portal del coneixement obert de la UPCinstname:Universitat Politècnica de Catalunya (UPC)Inglésengopen accesshttp://purl.org/coar/access_right/c_abf2http://creativecommons.org/licenses/by-nc-sa/4.0/info:eu-repo/semantics/openAccessoai:upcommons.upc.edu:2117/1274982026-05-27T15:37:01Z
score 15.300719

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