Coexisting Phases of Individual VO<sub>2</sub> Nanoparticles for Multilevel Nanoscale Memory

Vanadium dioxide (VO2) has received significant interest in the context of nanophotonic metamaterials and memories owing to its reversible insulator-metal transition associated with significant changes in its optical and electronic properties. The phase transition of VO2 has been extensively studied for several decades, and the ways how to control its hysteresis characteristics relevant for memory applications have significantly improved. However, the hysteresis dynamics and stability of coexisting phases during the transition have not been studied on the level of individual single-crystal VO2 nanoparticles (NPs), although they represent the fundamental component of ordinary polycrystalline films and can also act like nanoscale memory units on their own. Here, employing transmission electron microscopy techniques, we investigate phase transitions of single VO2 NPs in real time. Our analysis reveals the statistical distribution of the transition temperature and steepness and how they differ during forward (heating) and backward (cooling) transitions. We evaluate the stability of coexisting phases in individual NPs and prove the persistent multilevel memory at near room temperatures using only a few VO2 NPs. Our findings unveil the physical mechanisms that govern the hysteresis of VO2 at the nanoscale and establish VO2 NPs as a promising component of optoelectronic and memory devices with enhanced functionalities.

Keywords

vanadium dioxide, phase-change memory, nanophotonics, transmission electron microscopy, insulator-metaltransition, coexisting phases, hysteresis

Citation

ACS Nano (e-ISSN). 2025, vol. 19, issue 1, p. 1167-1176.
https://pubs.acs.org/doi/10.1021/acsnano.4c13188

Document type

Peer-reviewed

Document version

Published version

Language of document

en

Document licence

Creative Commons Attribution 4.0 International
http://creativecommons.org/licenses/by/4.0/