The insulator-metal phase transition in VO2 measured at nanometer length scales and femtosecond time scales

The physics of transition-metal oxides presents a challenge to our current understanding of condensed matter physics. The main difficulty arises from a competition between electron-electron and electron-phonon interactions to dictate the properties of these complex materials. This issue is particula...

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Bibliographic Details
Author: Vidas, Luciana
Format: doctoral thesis
Status:Published version
Publication Date:2019
Country:España
Institution:CBUC, CESCA
Repository:TDR. Tesis Doctorales en Red
OAI Identifier:oai:www.tdx.cat:10803/666959
Online Access:http://hdl.handle.net/10803/666959
https://dx.doi.org/10.5821/dissertation-2117-134615
Access Level:Open access
Keyword:Àrees temàtiques de la UPC::Física
535
539
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network_acronym_str ES
network_name_str España
repository_id_str
dc.title.none.fl_str_mv The insulator-metal phase transition in VO2 measured at nanometer length scales and femtosecond time scales
title The insulator-metal phase transition in VO2 measured at nanometer length scales and femtosecond time scales
spellingShingle The insulator-metal phase transition in VO2 measured at nanometer length scales and femtosecond time scales
Vidas, Luciana
Àrees temàtiques de la UPC::Física
535
539
title_short The insulator-metal phase transition in VO2 measured at nanometer length scales and femtosecond time scales
title_full The insulator-metal phase transition in VO2 measured at nanometer length scales and femtosecond time scales
title_fullStr The insulator-metal phase transition in VO2 measured at nanometer length scales and femtosecond time scales
title_full_unstemmed The insulator-metal phase transition in VO2 measured at nanometer length scales and femtosecond time scales
title_sort The insulator-metal phase transition in VO2 measured at nanometer length scales and femtosecond time scales
dc.creator.none.fl_str_mv Vidas, Luciana
author Vidas, Luciana
author_facet Vidas, Luciana
author_role author
dc.contributor.none.fl_str_mv Wall, Simon Elliot
Universitat Politècnica de Catalunya. Institut de Ciències Fotòniques
dc.subject.none.fl_str_mv Àrees temàtiques de la UPC::Física
535
539
topic Àrees temàtiques de la UPC::Física
535
539
description The physics of transition-metal oxides presents a challenge to our current understanding of condensed matter physics. The main difficulty arises from a competition between electron-electron and electron-phonon interactions to dictate the properties of these complex materials. This issue is particularly apparent in vanadium dioxide, which undergoes an electronic and structural phase transition close to room temperature. Despite more than 50 years of research, the origin of the transformation is still actively debated, with contradictory interpretations often reported. The main goal of this thesis is to re-evaluate the phase transition in VO2 with a combination of new experimental techniques, ranging from the midinfrared to hard x-rays, that can probe the transformation at nanometer length scales and femtosecond time-scales. This allows to disentangle the roles of phase separation, laser-induced heat, and electron and phonon dynamics to the insulator-metal transition. The results from these experiments provide a unified and new picture of the nature of this process, both in and out of equilibrium, in which the electron-phonon interactions are the main driving mechanism. Furthermore, the new techniques and analysis presented here for VO2 can be applied to the study of other controversial complex materials that exhibit remarkable properties, and answer thereby some of the key outstanding questions in condensed matter physics.
publishDate 2019
dc.date.none.fl_str_mv 2019
2019
2019
dc.type.none.fl_str_mv info:eu-repo/semantics/doctoralThesis
info:eu-repo/semantics/publishedVersion
format doctoralThesis
status_str publishedVersion
dc.identifier.none.fl_str_mv http://hdl.handle.net/10803/666959
https://dx.doi.org/10.5821/dissertation-2117-134615
url http://hdl.handle.net/10803/666959
https://dx.doi.org/10.5821/dissertation-2117-134615
dc.language.none.fl_str_mv Inglés
language_invalid_str_mv Inglés
dc.rights.none.fl_str_mv http://creativecommons.org/licenses/by-nc-nd/4.0/
info:eu-repo/semantics/openAccess
rights_invalid_str_mv http://creativecommons.org/licenses/by-nc-nd/4.0/
eu_rights_str_mv openAccess
dc.format.none.fl_str_mv 180 p.
application/pdf
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 TDX (Tesis Doctorals en Xarxa)
reponame:TDR. Tesis Doctorales en Red
instname:CBUC, CESCA
instname_str CBUC, CESCA
reponame_str TDR. Tesis Doctorales en Red
collection TDR. Tesis Doctorales en Red
repository.name.fl_str_mv
repository.mail.fl_str_mv
_version_ 1869418062141194241
spelling The insulator-metal phase transition in VO2 measured at nanometer length scales and femtosecond time scalesVidas, LucianaÀrees temàtiques de la UPC::Física535539The physics of transition-metal oxides presents a challenge to our current understanding of condensed matter physics. The main difficulty arises from a competition between electron-electron and electron-phonon interactions to dictate the properties of these complex materials. This issue is particularly apparent in vanadium dioxide, which undergoes an electronic and structural phase transition close to room temperature. Despite more than 50 years of research, the origin of the transformation is still actively debated, with contradictory interpretations often reported. The main goal of this thesis is to re-evaluate the phase transition in VO2 with a combination of new experimental techniques, ranging from the midinfrared to hard x-rays, that can probe the transformation at nanometer length scales and femtosecond time-scales. This allows to disentangle the roles of phase separation, laser-induced heat, and electron and phonon dynamics to the insulator-metal transition. The results from these experiments provide a unified and new picture of the nature of this process, both in and out of equilibrium, in which the electron-phonon interactions are the main driving mechanism. Furthermore, the new techniques and analysis presented here for VO2 can be applied to the study of other controversial complex materials that exhibit remarkable properties, and answer thereby some of the key outstanding questions in condensed matter physics.La física de los óxidos de metales de transición constituye un gran desafío a nuestra comprensión actual de la materia condensada. El mayor obstáculo surge de la competición entre las interacciones electrón-electrón y electrónfonón para dictar las propiedades de tales materiales complejos. Este problema es particularmente evidente en el dióxido de vanadio, el cual experimenta una transición de fase tanto electrónica como estructural a una temperatura ligeramente superior a la ambiente. A pesar de más de 50 años de investigaciones, el origen de la transformación sigue siendo motivo de debate, con multitud de interpretaciones a menudo contradictorias. El objetivo principal de esta tesis es reevaluar la transición aislante-metal de VO2 empleando una combinación de técnicas experimentales nuevas, desde la región del infrarrojo medio a los rayos X duros, que permiten el estudio de la transición de fase a escalas nanométricas y en tiempos de femtosegundos. Esto facilita el esclarecimiento de los roles que desempeñan aspectos como la separación de fases, el calor inducido por láser y las dinámicas de electrones y fonones en la transición de fase de VO2. Los resultados de estos experimentos ofrecen una visión unificada sobre la naturaleza de este fenómeno, tanto en equilibrio como fuera de él, en la que la interacción de los electrones con fonones son el principal mecanismo responsable de impulsar la transición. Asimismo, los análisis y técnicas nuevos presentados en esta tesis para el estudio de VO2 pueden ser empleados para la investigación de otros materiales complejos que también exhiben propiedades extraordinarias y cuyo entendimiento presenta serias controversias. De esta manera, se daría respuesta a algunas de las preguntas clave pendientes de la física de la materia condensada.DOCTORAT EN FOTÒNICA (Pla 2013)Universitat Politècnica de CatalunyaWall, Simon ElliotUniversitat Politècnica de Catalunya. Institut de Ciències Fotòniques201920192019info:eu-repo/semantics/doctoralThesisinfo:eu-repo/semantics/publishedVersion180 p.application/pdfapplication/pdfhttp://hdl.handle.net/10803/666959https://dx.doi.org/10.5821/dissertation-2117-134615TDX (Tesis Doctorals en Xarxa)reponame:TDR. Tesis Doctorales en Redinstname:CBUC, CESCAInglésL'accés als continguts d'aquesta tesi queda condicionat a l'acceptació de les condicions d'ús establertes per la següent llicència Creative Commons: http://creativecommons.org/licenses/by-nc-nd/4.0/http://creativecommons.org/licenses/by-nc-nd/4.0/info:eu-repo/semantics/openAccessoai:www.tdx.cat:10803/6669592026-06-14T12:46:07Z
score 15.301603

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