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DTSTART;VALUE=DATE:20251106T101500
DTEND;VALUE=DATE:20251106T101500
UID:18820@agenda.unifr.ch
DESCRIPTION:Prominent features in the optical spectrum of materials can be \ndeeply connected to its electronic structure.  \nTriggering an ultrafast change using ultrashort laser pulses may lead \nto the excitation of coherent phonon modes, such as in the case of \nthe type-II Weyl semimetal WTe2, where these collective vibrations \nlead to a periodic change of the band structure. We examine the \nimpact on the effective mass of the electron and hole pockets \nthrough broadband white light and X-ray diffraction and discuss the \nconsequences on WTe2’s magnetoresistance and topological \nproperties. \nAlternatively, resonant excitations via specific band transitions may \nlead to a control of element-specific electronic configurations. \nFeCr2S4 is a spinel ferrimagnet where the magneto-optical Kerr \nrotation peaks in correspondence of the intra-atomic Fe d-d \ntransitions in the mid-infrared. We show how a resonant excitation \nof the material through this pathway leads to a significantly different \ntimescale of the magneto-optical dynamics compared to the non\nresonant case and discuss its impact on the superexchange \ninteraction within the system. 
SUMMARY:Ultrafast interplay between band structure and optics:  phonon dynamics in WTe2 and MOKE in ferrimagnetic  FeCr2S4
CATEGORIES:Séminaire
LOCATION:PER 08\, 0.58.5\, Chemin du Musée 3\, 1700 Fribourg
URL;VALUE=URI:https://agenda.unifr.ch/e/fr/18820
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