2023 年 66 巻 8 号 p. 455-460
Layered oxyfluoride single-crystalline thin films of Sr2RuO3F2, Ca2RuO2.5F2, and Sr2IrO2.5F3 were fabricated via topochemical fluorination. All the fluorinated films exhibited an insulating behavior and a largely expanded c-axis than the precursors. Sr2RuO3F2 film was a Mott insulator with Ru4+ states and had two inequivalent F- sites in the SrO layers. In contrast, Ca2RuO2.5F2 film had the Ru3+ state and only one F- site in the CaO rock-salt blocks. This discrepancy is probably due to the larger lattice distortion in the Ca2RuO4 precursor. The conduction mechanism of Ca2RuO2.5F2 film was described by two-dimensional variable range hopping. The effective total angular momentum Jeff=3/2 of Sr2IrO2.5F3 film was stabilized upon fluorination owing to the large electronegativity of fluorine. The conduction mechanism of Sr2IrO2.5F3 film was described by Efros-Shklovskii variable-range hopping. These results will be useful for modifying electronic states by anion doping to explore unprecedented electronic properties in layered oxides.