Nanoscale self-organization and metastable non-thermal metallicity in Mott insulators

• Published in: Nature communications Vol. 13; no. 1; pp. 3730 - 14
• Main Authors: Ronchi, Andrea, Franceschini, Paolo, De Poli, Andrea, Homm, Pía, Fitzpatrick, Ann, Maccherozzi, Francesco, Ferrini, Gabriele, Banfi, Francesco, Dhesi, Sarnjeet S., Menghini, Mariela, Fabrizio, Michele, Locquet, Jean-Pierre, Giannetti, Claudio
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 28.06.2022; Nature Publishing Group; Nature Portfolio
• Subjects: 639/766/119/2795; 639/766/119/995; Chemical Sciences; Corundum; Engineering Sciences; Equilibrium; Excitation; High temperature; Humanities and Social Sciences; Insulators; Light; Low temperature; Metal-insulator transition; Metallicity; Metastable state; Microscopy; Monoclinic lattice; multidisciplinary; Phase transitions; Physics; Science; Science (multidisciplinary); Shear strain; Strain; Thin films; Vanadium oxides; X ray microscopy
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/s41467-022-31298-0

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. Here, we combine time-resolved X-ray microscopy with a Landau-Ginzburg functional approach for calculating the strain and electronic real-space configurations. We investigate V 2 O 3 , the archetypal Mott insulator in which nanoscale self-organization already exists in the low-temperature monoclinic phase and strongly affects the transition towards the high-temperature corundum metallic phase. Our joint experimental-theoretical approach uncovers a remarkable out-of-equilibrium phenomenon: the photo-induced 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. Mott metal-insulator transition in real materials is characterized by complex lattice and electron dynamics involving multiple length and time scales. Here, by combining time-resolved experimental probe and coarse-grained modelling, the authors elucidate the nanoscale dynamics across the Mott transition in V 2 O 3 .