[seminar] Seminar at the Institute of Physics, Thursday September 30th 2021 at 11:00, room ``Mladen Paić", 3rd wing, and Zoom

[Ivan Balog]

Seminar at IF, Thursday September 30th 2021 at 11:00, room ``Mladen Paić", 3rd wing, and Zoom 

Photo - induced structural dynamics in Magnetit e 
D r .Siham Benhabib 
EPFL , Lausanne, Switzerland 

The complex interplay between crystal structure, charge, and orbital orders leads magnetite to undergo atypical metal - insulator transition in the neighborhood of 125 K known by Verwey Transition (VT). Despite the numerous approaches that have been adopted in the last 80 years, the leading mechanism of VT in magnetite still remains ambiguous. Here we use ultrafast electron diffraction (UED) to trace the structura l changes of magnetite across the VT in the thermodynamic equilibrium and the ultrafast dynamics response of the structure under femtosecond pulsed excitations. Specifically, we study the strain evolution in magnetite following two major steps. First, in the thermodynamic equilibrium, we used symmetry arguments to determine the symmetry of the order parameter responsible for strain changes across VT. Second, out - of - equilibrium evolution: we investigated strain behavior under femtosecond pulsed light excit ations. We used two excitations, 800 nm and 400nm (1.6 and 3.09 eV, respectively). These investigations are carried out in two phases, above and below VT termed as High Temperature (HT) and Low Temperature (LT) phases. In the LT phase, we distinguish two d ifferent time evolution of the strain depending on the excitation’s energy. This difference is absent in the HT phase. We presume this difference is intimately linked to the mechanism of VT. In this presentation, I will discuss the possible scenarios respo nsible for such differences in the dynamic responses 

Seminar hosts: [ mailto:balog at ifs.hr | Ivan Balog ] i [ mailto:ddominko at ifs.hr | Damir Dominko ] 
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Potičemo slušatelje da, zbog epidemiološke situacije, u što većem broju prate seminar ``on-line" putem Zooma. 

https://zoom.us/j/5081440931 

Meeting ID: 508 144 0931 


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Due to the epidemiological situation, we encourage the audience to follow the seminar on-line via Zoom. 


https://zoom.us/j/5081440931 

Meeting ID: 508 144 0931 

-- 
Ivan Balog
Research associate
Institute of Physics Zagreb
Bijenicka cesta 46,
10000 Zagreb, Croatia
office: +385 1 469 8908 e-mail: [ mailto:ddominko at ifs.hr | balog at ifs.hr ] 

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