Strain-assisted topochemical synthesis of la-doped SrVO2H Films
Résumé
Perovskite oxyhydride SrVO2H (V3+, d2) is a Mott insulator with a strong two-dimensional correlation due to anion ordering. In this study, we attempted electron doping by aliovalent substitution. Although Sr1-xLaxVO3 thin films (x ≤ 0.4) on a SrTiO3 substrate were topochemically reduced using CaH2, vanadium of the reduced films retained the trivalent state. Combined with the results of secondary ion mass spectroscopy, we conclude that Sr1-xLaxVO2+xH1-x is obtained, where the apical oxygen site is partially replaced by hydride anions. First-principles theoretical calculations highlight the role played by compressive biaxial strain in stabilizing the charge-compensated Sr1-xLaxVO2+xH1-x phase, rather than the electron-doped Sr1-xLaxVO2H. The present study demonstrates that topochemical reactions combined with substrate strain provide various opportunities to widen the compositional space in mixed-anion compounds. ©
Mots clés
Calculations
Lanthanum compounds
Mott insulators
Negative ions
Perovskite
Secondary ion mass spectrometry
Semiconductor doping
Strontium titanates
Thin films
Aliovalent substitution
Mixed-anion compounds
Secondary ion mass spectroscopy
SrTiO3 substrates
Substrate strain
Theoretical calculations
Topochemical reaction
Two-dimensional correlation
Vanadium compounds