Berlin 2024 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 81: Nanostructures at Surfaces I

O 81.3: Vortrag

Donnerstag, 21. März 2024, 11:00–11:15, MA 042

Intermediate metal-insulator phases of individual VO₂ nanocrystals for multilevel memory — Peter Kepič, Michal Horák, Jiří Kabát, Filip Ligmajer, Andrea Konečná, and •Vlastimil Křápek — Brno University of Technology, Czechia

Vanadium dioxide (VO₂) is a strongly correlated material that exhibits metal-insulator transition (MIT) around 340 K [1]. A broad conductivity hysteresis of VO₂ is vital for its applications as memory or memristor devices. In our contribution, we study the hysteresis of temperature-induced MIT in individual high-density VO₂ nanocrystals using analytical electron microscopy. We utilize low-loss and core-loss electron energy loss spectroscopy (EELS) combined with in-situ heating to analyze the metal-insulator transition [2] in more than 40 nanocrystals. We retrieve the parameters of the hysteresis loop and demonstrate their dependence on the size of the nanocrystals. Interestingly, some nanocrystals exhibit switching from the insulating to the metallic phase by parts, with the intermediate phases allowing to design multilevel memory. We also show by correlating the image contrast with EELS that signatures of MIT are observable simply and efficiently using annular dark-field imaging.

[1] P. Kepič et al., ACS Photonics 8, 1048 (2021).

[2] J. Krpenský, M. Horák et al., arXiv 2309.11980.