# Valley-controlled photoswitching of metal–insulator nanotextures

## TL;DR

Researchers show a new way to control material phase transitions using valley-selective light, enabling precise nanoscale engineering with minimal heat.

## Contribution

Valley-selective photodoping enables domain-specific phase control in Peierls insulators with minimal electronic heating.

## Key findings

- Valley-selective photodoping initiates an insulator–metal transition in subwavelength domains.
- Minimal electronic heating allows for domain-specific carrier confinement and phase control.
- The method enables optically controlled hidden states and engineered heterostructures.

## Abstract

Spatial heterogeneity and phase competition are hallmarks of strongly correlated materials, influencing phenomena such as colossal magnetoresistance and high-temperature superconductivity. Active control over phase textures further promises tunable functionality at the nanoscale. Although light-induced switching of a correlated insulator to a metallic state is well established, optical excitation generally lacks the specificity to select subwavelength domains and determine final textures. Here we drive the domain-specific quench of a textured Peierls insulator using valley-selective photodoping. Polarized excitation exploits the anisotropy of quasi-one-dimensional states at the charge-density-wave gap to initiate an insulator–metal transition with minimal electronic heating. We find that averting dissipation facilitates domain-specific carrier confinement, control over nanotextured phases and reduction in thermal relaxation from the metastable metallic state. This valley-selective photoexcitation approach will enable the activation of electronic phase separation beyond thermodynamic limitations, facilitating optically controlled hidden states, engineered heterostructures and polarization-sensitive percolation networks.

Optical excitation is a way to control phase transitions in materials, but it lacks spatial specificity. Now, valley-selective photodoping in a Peierls insulator is demonstrated as a method to optically engineer phase textures with minimal heating.