Seminars Archive

Topological non-thermal resistive switching in a V2O3-based Mott device

Claudio Giannetti
Dipartimento di Matematica e Fisica, Università Cattolica del Sacro Cuore, Brescia

Abstract
Resistive switching is the most fundamental and universal process which triggers the sudden change of the electrical properties of solid-state devices under the action of an intense electric field. The insulator-to-metal transition in Mott materials is one of the most investigated mechanisms that can lead to a local and ultrafast resistance drop in Mottronic devices [1]. Despite its huge technological impact [2-4] on information processing, ultrafast electronics, neuromorphic computing and resistive memories, resistive switching still remains an unpredictable, irreproducible and elusive phenomenon, whose dynamics is uncontrolled. The intrinsic intertwining of the electronic and structural degrees of freedom in Mott materials adds further complexity to the problem. Here, we report synchrotron X-ray Photoemission Electron Microscopy (PEEM) imaging of the resistive switching process in a V2O3-based device. The insulating phase of V2O3 is characterized by a complex nanotexture of the three equivalent monoclinic twins oriented along the three hexagonal axes of the high-temperature rhombohedral phase [5]. The possibility of imaging the early-stage formation of nanometric metallic channels during the application of an above-threshold electric field, sheds unexpected light on the switching process. We show that the formation of the metallic filaments is pinned by strain topological defects that spontaneously form at the crossing point of different monoclinic domains. We also note that the first resistive drop leaves the monoclinic nanotexture unchanged, thus suggesting the possibility of a purely electronic and non-thermal nature of the process [6,7]. Our results pave the way to the use of strain engineering approaches to manipulate the topology of the monoclinic nanotexture and achieve full control of the all-electronic resistive switching process. References: [1] Y. Tokura, M. Kawasaki, and N. Nagaosa, Emergent functions of quantum materials, Nature Physics 13, 1056 (2017) [2] J. Del Valle et al. Subthreshold firing in Mott nanodevices, Nature 569, 388 (2019) [3] J. Del Valle et al. Challenges in materials and devices for resistive-switching-based neuromorphic computing. Journal of Applied Physics 124, 211101 (2018) [4] Z. Wang et al. Resistive switching materials for information processing, Nature Reviews Materials 5, 173 (2020) [5] A. Ronchi et al. Nanoscale self-organization and metastable non-thermal metallicity in Mott insulators, Nature Communications 13, 3730 (2022). [6] A. Ronchi et al. Early-stage dynamics of metallic droplets embedded in the nanotextured Mott insulating phase of V2O3, Physical Review B 100, 075111 (2019) [7] A. Ronchi et al. Light-assisted resistance collapse in a V2O3-based Mott-insulator device, Physical Review Applied 15, 044023 (2021)