Universal phase dynamics in VO<sub>2</sub> switches revealed by ultrafast operando diffraction.

Sood, Aditya; Shen, Xiaozhe; Shi, Yin; Kumar, Suhas; Park, Su Ji; Zajac, Marc; Sun, Yifei; Chen, Long-Qing et al. · Science · 2021

basic_science · Level V

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Abstract

Understanding the pathways and time scales underlying electrically driven insulator-metal transitions is crucial for uncovering the fundamental limits of device operation. Using stroboscopic electron diffraction, we perform synchronized time-resolved measurements of atomic motions and electronic transport in operating vanadium dioxide (VO<sub>2</sub>) switches. We discover an electrically triggered, isostructural state that forms transiently on microsecond time scales, which is shown by phase-field simulations to be stabilized by local heterogeneities and interfacial interactions between the equilibrium phases. This metastable phase is similar to that formed under photoexcitation within picoseconds, suggesting a universal transformation pathway. Our results establish electrical excitation as a route for uncovering nonequilibrium and metastable phases in correlated materials, opening avenues for engineering dynamical behavior in nanoelectronics.