Revealing the Role of Hydrogen in Electron-Doping Mottronics for Strongly Correlated Vanadium Dioxide

Abstract

Hydrogen-associated electron-doping Mottronics for d-band correlated oxides (e.g., VO 2 ) opens up a new paradigm to regulate the electronic functionality via directly manipulating the orbital configuration and occupancy. Nevertheless, the role of hydrogen in the Mottronic transition of VO 2 is yet unclear because opposite orbital reconfigurations toward either the metallic or highly insulating states were both reported. Herein, we demonstrate the root cause for such hydrogen-induced multiple electronic phase transitions by 1 H quantification using nuclear reaction analysis. A low hydrogenation temperature is demonstrated to be vital in achieving a large hydrogen concentration (n H ≈ 10 22 cm −3 ) that further enhances the t 2g orbital occupancy to trigger electron localizations. In contrast, elevating the hydrogenation temperatures surprisingly reduces n H to ∼10 21 cm −3 but forms more stable metallic H 0.06 VO 2 . This leads to the recognition of a weaker hydrogen interaction that triggers electron localization within VO 2 via Mottronically enhancing the orbital occupancies.

Manipulating the metal-to-insulator transitions of VO2 by combining compositing and doping strategies

“…Similar to other correlated oxides, a small-polaron hopping model is expected for carrier transport in insulating VO 2 . 27,28 As shown in Fig. 3d, their thermal activation energies (E a ) were plotted as a function of the nominal concentration in comparison with the pristine VO 2 bulk.…”

Giant Resistive Switching and Lattice Modulation at Full Temperature Range in a Sr‐Doped Nickelate Oxide Transistor

“…[ 16–19 ] Under positive potential, protons intercalate into the NSNO lattice accompanied by uptake of electrons released by oxidation at the counter electrode in order to remain electrically neutral. [ 20,21 ] With one more electron, Ni 3+ $$t_{2{\rm{g}}}^6e_{\rm{g}}^1$$ from metallic NSNO is converted into insulating Ni 2+ $$t_{2{\rm{g}}}^6e_{\rm{g}}^2$$, owing to strong Coulomb repulsion between e g electrons of Ni 2+ which causes a large Mott–Hubbard splitting (Figure 1c). [ 8 ]…”

Voltage Control of Patterned Metal/Insulator Properties in Oxide/Oxyfluoride Lateral Perovskite Heterostructures via Ion Gel Gating

“…While not demonstrated here, we hypothesize that the spatial selectivity of ionic conductivity (as in the case of oxygen herein or other cationic‐diffusive oxides such as VO 2 , [ 56 ] WO 3 , [ 57,58 ] perovskite nickelates, [ 36 ] and perovskite ruthenates [ 59,60 ] ), as well as thermal conductivity, [ 61,62 ] could be similarly controlled by gate‐induced electrochemical transformations. This would enable reversible and dynamic control of charge or heat flow for Mottronic [ 63,64 ] and thermal devices, [ 65 ] respectively.…”