Lawrence Berkeley National Laboratory

Abstract The ability to control material heat transport properties over space and time can drive advanced functionalities in thermal management for electronics and system‐on‐chip, and enable thermal circuits. Despite the technological relevance, there are limited demonstrations of local thermal property control. Rotating lattice single (RLS) crystals—formed via laser‐induced crystallization of an amorphous substrate—offer a novel avenue for local crystal engineering, unlocking opportunities for microscale property patterning. Here, thermal conductivity (𝜅) imaging is applied to RLS crystals of Sb 2 S 3 to resolve microscale 𝜅 variations across patterned regions. Amorphous areas exhibit 𝜅 as low as 0.6 Wm −1 K −1 , while crystalline regions display periodic 𝜅 variations from 0.7 to over 2.5 Wm −1 K −1 . These variations correspond to changes in crystal orientation, revealing marked 𝜅 anisotropy. The crystal out‐of‐plane direction (c axis)—featuring van der Waals bonds—shows amorphous‐like transport, whereas in‐plane directions (a, b axes) exhibit 3.5x and 1.7x larger 𝜅, respectively. First‐principles calculations, in excellent agreement with experiments, suggest that the in‐plane anisotropy originates from expressed Sb lone pairs, which impart a corrugation along the b axis affecting bond stiffness and 𝜅. These findings demonstrate microscale control of thermal properties via laser‐processed metastructures, with significant implications for next‐generation thermal management.