Berlin 2024 – wissenschaftliches Programm
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MM: Fachverband Metall- und Materialphysik
MM 16: Poster Ia
MM 16.6: Poster
Montag, 18. März 2024, 18:30–20:30, Poster E
Phase transitions and electronic properties of Fe2O3 under laser compression by ultrafast in-situ X-ray absorption spectroscopy — Juan Pintor1, Delphine Cabaret2, and •Marion Harmand3 — 1IMPMC, Sorbonne University, Paris, France. — 2IMPMC, Sorbonne University, Paris, France. — 3IMPMC, Sorbonne University, Paris, France.
Understanding the structural changes in hematite (α-Fe2O3) under extreme pressure and temperature is essential for gaining insights into the physical properties of planetary interiors. At ambient conditions, hematite exhibits a rhombohedral structured antiferromagnetic insulator. Its high-pressure behavior has been extensively studied, with particular focus on pressures around 50 GPa, revealing a 10% volume cell drop, a change in crystal symmetry, a Mott transition, and the collapse of iron magnetic moments ( high-spin to low-spin transition). The exact nature of the phase transition in this pressure range remains controversial, with debates about whether the electronic or structural transition drives the other. This study reports ultrafast time-resolved X-ray Absorption Near Edge Spectroscopy (XANES) measurements conducted at the High Power Laser Facility of ESRF-ID24 beamline. Our data capture time-resolved transformations, revealing changes in the different XANES features within hundreds of ps, after the shock breakout from the samples. This presentation will detail a time-resolved examination of XANES changes with respect to pressure and temperature. For further understanding of the XANES features, preliminary DFT calculations will also be presented.
Keywords: phase transitions; dynamic compression; laser shock; X-ray absorption spectroscopy; ab initio calculations