Valley-controlled photoswitching of metal-insulator nanotextures.

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.