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

TL;DR

This study reveals how nanoscale self-organization in Mott insulators like V₂O₃ enables the stabilization of a metastable monoclinic metallic phase through light excitation, combining experimental and theoretical insights.

Contribution

It demonstrates the light-induced stabilization of a metastable monoclinic metal phase in a Mott insulator, highlighting the role of nanotexture and non-thermal states.

Findings

Nanoscale self-organization influences phase transitions in V₂O₃.

Light excitation stabilizes a metastable monoclinic metallic phase.

Experimental and theoretical methods reveal the role of nanotexture in non-thermal states.

Abstract

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.