HYBRID \;DEFENCE: REG ISTER \;HERE \;to attend
\nDirectors: Prof. Klaas-Jan Tielrooij\, \;Ultrafast Dynamics in Nanoscale Syst ems \;Senior Group Leader at ICN2.
\nShort Abstract: \;It has been a longs tanding goal of physicists to understand how heat flows and how it affects the thermal properties of materials. This quest has been driven not only by the pursuit of knowledge but also by the tremendous importance of heat in daily life. The discovery of new materials has introduced challenges in understanding fundamental properties such as heat transport\, while also opening avenues for technological advancements. In this thesis\, we invest igate the heat transport properties of a class of layered materials known as transition metal dichalcogenides (TMDs). We study these materials using two different optical techniques: the conventional technique of Raman the rmometry and a novel spatiotemporal pump-probe thermometry technique that we have developed. With this new technique\, we directly quantify the in-p lane thermal diffusivity in TMDs. The thermal diffusivities obtained for M oSe2\, down to a thickness of 3 layers\, are consistent with results obtai ned from Raman thermometry. Interestingly\, in monolayer and bilayer sampl es\, we observe a transition in heat transport behaviour—from diffusive in thicker samples to viscous with very low diffusivity in ultrathin sampl es. We attribute this viscous transport to the hydrodynamic flow of heat\, a phenomenon that has never been observed in TMDs at any temperature.
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DTSTART:20241028T133000 DTEND:20241028T225959 LOCATION:ICN2 Seminar Hall\, ICN2 Building\, Campus UAB CATEGORIES:ICN2 Theses Defence END:VEVENT END:VCALENDAR