Abstract : Materials exhibiting luminescence stimuli-responsive properties, present potential application as detection systems. Among these materials, copper (I) iodide molecular clusters coordinated by phosphine ligands, exhibit thermochromic and mechanochromic luminescence properties. These compounds are characterized by a change of their emission wavelength in response to temperature or mechanical stress. The establishment of structure- properties relationships permit to study the mechanisms responsible for their properties. The main characterization techniques used are solid-state NMR, X-ray diffraction, Infrared and Raman spectroscopies. In addition to the thermo and mechanochromic properties, these compounds have the particularity of exhibiting aggregation-induced emission (AIE) properties. The understanding of properties is crucial for applications. Therefore, DFT (Density Functional Theory) calculations are also carried out to rationalize the different results and in particular the optical properties. In the last years, copper has been proposed as a substituent in lead perovskite-based devices due to its non-toxic nature. We are currently investigating the use of copper perovskites for solar cells.

Speaker : Thomas Cottineau (Equipe Photocatalyse & Photoconversion –
Institut de Chimie et Procédés pour l’Energie, l’Environnement et la Santé
(ICPEES UMR 7515 CNRS / Université de Strasbourg)

Abstract

Speaker: Paul STEADMAN (Responsable de la ligne I10 au Synchroton Diamond)

Abstract : A study of the electric current induced hysteresis in Pt/CoFeTaB thin films revealed an unexpected behaviour in the hysteresis curves measured using polarised soft X-ray reflectivity [1]. Following a detailed study of the polarisation dependence of the reflected intensity [2] both detailed calculations and experimental data revealed that the switching is Y type (magnetisation switching perpendicular to the current), is very sensitive to external magnetic fields and that, rather bizarrely, only part of the film is switching. In addition the importance of non-linear dependence on the magnetic scattering and its dependence on polarisation and energy have been uncovered experimentally and explained with a very simple model.

• [1] D. M. Burn, R. Fan, O. Inyang, M. Tokac¸ L. Bouchenoire, A. T. Hindmarch and P. Steadman, P. (2022). Phys. Rev. B, 106, 094429.
• [2] Raymond Fan, Kiranjot, Razan O. M. Aboljadayel, Kalel Alsaeed, Peter, J. Synchrotron Rad. (2024). 31, 493–507

Kevin Dedecker (Institut Européen des Membranes (IEM); CNRS, ENSCM, Univ Montpellier)

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