Revealing the role of high-valence elementary substitution in the hydrogen-induced Mottronic transitions of vanadium dioxide

Abstract

Electron-doping Mottronics within correlated vanadium dioxide (e.g., VO2) opens up a paradigm to abruptly regulate the Mottronic phase transitions via adjusting the d-orbital occupancy and configuration. Nevertheless, the potential impact of high-valence elementary substitution in the hydrogen-associated Mottronic transitions of VO2 is yet unclear. Herein, we demonstrate the role of high-valence elementary substitution (e.g., W6+) in regulating the hydrogen-triggered Mottronic transitions of VO2, assisted by quantitative hydrogen analysis using the nuclear reaction analysis. Substituting vanadium with a high-valence transitional metal (e.g., W6+) within doped-VO2 largely reduces the hydrogen incorporation (e.g., ∼1.61 × 1021 cm−3 in H0.06V0.95W0.05O2) compared to the intrinsic VO2 (e.g., ∼1.08 × 1022 cm−3 in H0.35VO2) under the low temperature hydrogenation process. Therefore, in contrast to hydrogen-induced electron localization of intrinsic VO2 upon low-temperature hydrogenation, only the hydrogen-triggered metallic state is observed within the hydrogen-associated phase diagram of WxV1-xO2, as further probed by the near-edge x-ray absorption fine structure analysis and x-ray photoelectron spectroscopy. The present work reveals the overlooked role associated with the donor substitutions that largely influences the competitive equilibrium between the two rival hydrogen-induced Mottronic transitions within VO2 toward either the metallic or the highly insulating phase.

Epitaxy of Monoclinic VO2 on Large-Misfit 3m Template Enabled by a Metastable Interfacial Layer

“…As one of the most intensively studied strongly correlated oxides, VO 2 is featured by an abrupt metal–insulator transition (MIT) near room temperature (∼340 K), which is accompanied by a monoclinic-to-rutile structural change. , Such a MIT makes VO 2 very attractive for a vast variety of potential applications such as ultrafast switches, smart windows, infrared imaging, Mottronics, and memristors. − In addition, notable is that the strong coupling among lattice, charge, spin, and orbital degrees of freedom provides additional knobs for manipulating its intrinsic properties and seeking new conceptual devices, through external stimuli including strain, electric and optical fields. − For instance, both the electrically driven and photoinduced MITs in VO 2 have been demonstrated to be fascinating ways to achieve neuromorphic computing for overcoming the limitations of von Neumann architectures. , In addition, huge piezoresistive response which is an order of magnitude larger than that of silicon was observed in the VO 2 nanomembrane, opening the door to the ultrasensitive, low-power-dissipation tactile sensors …”

“… 1 , 2 Such a MIT makes VO 2 very attractive for a vast variety of potential applications such as ultrafast switches, smart windows, infrared imaging, Mottronics, and memristors. 3 − 6 In addition, notable is that the strong coupling among lattice, charge, spin, and orbital degrees of freedom provides additional knobs for manipulating its intrinsic properties and seeking new conceptual devices, through external stimuli including strain, electric and optical fields. 7 − 10 For instance, both the electrically driven and photoinduced MITs in VO 2 have been demonstrated to be fascinating ways to achieve neuromorphic computing for overcoming the limitations of von Neumann architectures.…”