Nanoscale self-organisation in Mott insulators: a richness in disguise Andrea Ronchi, 1, 2, 3, ∗ Paolo Franceschini, 1, 2, 3 Andrea De Poli, 1, 2, 4 Pía Homm, 3 Ann Fitzpatrick, 5 Francesco Maccherozzi, 5 Gabriele Ferrini, 1, 2 Francesco Banfi, 6 Sarnjeet S. Dhesi, 5 Mariela Menghini, 3, 7 Michele Fabrizio, 4, † Jean-Pierre Locquet, 3 and Claudio Giannetti 1, 2, ‡ 1 Department of Physics, Università Cattolica del Sacro Cuore, Brescia I-25133, Italy 2 ILAMP (Interdisciplinary Laboratories for Advanced Materials Physics), Università Cattolica del Sacro Cuore, Brescia I-25133, Italy 3 Department of Physics and Astronomy, KU Leuven, Celestijnenlaan 200D, 3001 Leuven, Belgium 4 Scuola Internazionale Superiore di Studi Avanzati (SISSA), Via Bonomea 265, 34136 Trieste, Italy 5 Diamond Light Source, Didcot, Oxfordshire, OX11 0DE, UK 6 FemtoNanoOptics group, Université de Lyon, CNRS, Université Claude Bernard Lyon 1, Institut Lumière Matière, F-69622 Villeurbanne, France 7 IMDEA Nanociencia, Cantoblanco, 28049, Madrid Spain Mott transitions in real materials are first order and almost always associated with lattice distortions, both features promoting the emergence of nanotextured phases. This nanoscale self-organization creates spatially inhomogeneous regions, which can host and protect transient non-thermal electronic and lattice states triggered by light excitation. However, to gain full control of the Mott transition for potential applica- tions in the field of ultrafast switching and neuromorphic computing it is necessary to develop novel spatial and temporal multiscale experimental probes as well as theoret- ical approaches able to distill the complex microscopic physics into a coarse-grained modelling. Here, we combine time-resolved X-ray microscopy, which snaps phase transformations on picosecond timescales with nanometric resolution, with a Landau-Ginzburg func- tional approach for calculating the strain and electronic real-space configurations. We investigate V2O3, the archetypal Mott insulator in which nanoscale self-organization already exists in the low-temperature monoclinic phase and strongly affects the transi- tion towards the high-temperature corundum metallic phase. Our joint experimental- theoretical approach uncovers a remarkable out-of-equilibrium phenomenon: the pho- toinduced stabilisation of the long sought monoclinic metal phase, which is absent at equilibrium and in homogeneous materials, but emerges as a metastable state solely when light excitation is combined with the underlying nanotexture of the monoclinic lattice. Our results provide full comprehension of the nanotexture dynamics across the insulator-to-metal transition, which can be readily extended to many families of Mott insulating materials. The combination of ultrafast light excitation and spatial nan- otexture turns out to be key to develop novel control protocols in correlated quantum materials. ∗ andrea.ronchi@unicatt.it † fabrizio@sissa.it ‡ claudio.giannetti@unicatt.it arXiv:2109.05116v1 [cond-mat.str-el] 10 Sep 2021