Unravelling a photoinduced compressive lattice response in the canonical Mott insulator (V1-xCrx)2O3

This proposal aims at determining the nature of lattice strain, compressive vs tensile, following the ultrafast photoexcitation of hot carriers in the canonical Mott insulator (V1-xCrx)2O3. Our recent µ-XRD mapping on (V0.95Cr0.05)2O3 thin films after an electric field-driven insulator to metal transition indeed revealed a compressive lattice response. As electric field and light pulses are both prone to generate hot carriers, we might expect that photoexcitation would also induce a compressive lattice response in (V1 - xCrx)2O3. Our preliminary pump-probe reflectivity study in (V0.95Cr0.05)2O3 films is consistent with this view. Overall this study might challenge the paradigm by which photoexcitation of matter always leads to a thermally-driven expansion, and suggest that Mott physics can lead to a reverse compressive behavior. This study is part of the MOTT-IA project, which aims at creating the first hardware neural network based on the properties of Mott insulators.