8-12 July 2013
Africa/Johannesburg timezone
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Observation of structural dynamics of 1T-TiSe2 using femtosecond electron diffraction

Presented by Ms. Aminat Oyiza SULEIMAN on 9 Jul 2013 from 16:00 to 16:20
Type: Oral Presentation
Session: Photonics
Track: Track C - Photonics

Abstract

Trilayered transition metal dichalcogenides such as our sample 1T-TiSe<sub>2</sub> have been studied for many years as systems with strong electron-electron and electron-phonon correlations. The main attraction to this family of compound is its potential to exhibit a ground state phenomenon known as charge density waves whose detailed physical origin has been controversially determined. We shall be using an ultrafast femtosecond laser based on pump-probe technique, namely ultrafast electron diffraction, to investigate some of the noble features associated with this crystal. A pump laser pulse excites the crystal from its ground state and the probe pulse (ultrashort electron pulse) takes the snapshot of this evolution of the lattice generating an electron diffraction pattern of this crystal. Hence the dynamical structural behaviour can be observed in time with a subpicosecond temporal resolution. As a hexagonal close-packed structure, its signature is expected to be seen in the diffraction pattern as has been observed by Woo <i>et al</i> in steady state transmission electron diffraction. Time-resolved measurements as well as the behaviour of the charge density wave for various pump fluences shall be investigated. We investigate the suppression of the charge density wave (CDW) order, measure the electron-phonon coupling time, and determine the CDW recovery process. With sufficient pumping fluence we might see a high temperature CDW phase appearing in the diffraction patterns. Email: suleiman@sun.ac.za

Award

Yes

Level

MSc

Supervisor

Prof. Heinrich Schwoerer heso@sun.ac.za Stellenbosch University

Paper

No

Place

Location: A1-11


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