Photoinduced hidden monoclinic metallic phase of VO2 driven by local nucleation
Feng-Wu Guo, Wenhao Liu, Zhi Wang, Shu-Shen Li, Lin‐Wang Wang, Jun‐Wei Luo
Abstract
The insulator-to-metal transition in VO2 has garnered extensive attention for its potential applications in ultrafast switches, neuronal network architectures, and storage technologies. However, the photoinduced insulator-to-metal transition remains controversial, especially whether a complete structural transformation from the monoclinic to rutile phase is necessary. Here we employ the real-time time-dependent density functional theory to track the dynamic evolution of atomic and electronic structures in photoexcited VO2, revealing the emergence of a long-lived monoclinic metal phase under low electronic excitation. The emergence of the metal phase in the monoclinic structure originates from the dissociation of the local V-V dimer, driven by the self-trapped and self-amplified dynamics of photoexcited holes, rather than by an electron-electron correction. On the other hand, the monoclinic-to-rutile phase transition does appear at higher electronic excitation. Our findings validate the existence of monoclinic metal phase and provide a comprehensive picture of the insulator-to-metal transition in photoexcited VO2. Vanadium dioxide exhibits an insulator-to-metal transition when exciting by a laser. Here, the authors show the transition arises from the dissociation of local V-V dimers and show the existence of the monoclinic metallic phase from ab initio simulations.