Anion Doping of Ferromagnetic Thin Films of La0.74Sr0.26MnO3−δ via Topochemical Fluorination

Abstract

Chemical doping via insertion of ions into the lattice of a host material is a key strategy to flexibly manipulate functionalities of materials. In this work, we present a novel case study on the topotactic insertion of fluoride ions into oxygen-deficient ferromagnetic thin films of La0.74Sr0.26MnO3−δ (LSMO) epitaxially grown onto single-crystal SrTiO3 (STO) substrates. The effect of fluorination on the film structure, composition, and magnetic properties is compared with the case of oxygen-deficient and fully-oxidized LSMO films. Although incorporation of F− anions does not significantly alter the volume of the LSMO unit cell, a strong impact on the magnetic characteristics, including a remarkable suppression of Curie temperature and saturation magnetization accompanied by an increase in magnetic coercivity, was found. The change in magnetic properties can be ascribed to the disruption of the ferromagnetic exchange interactions along Mn-anion-Mn chains driven by F− doping into the LSMO lattice. Our results indicate that F− doping is a powerful means to effectively modify the magnetic functional properties of perovskite manganites.

Physical properties of epitaxial SrMnO2.5−δ F γ oxyfluoride films

“…It was reported that the fluorination of bulk SrMnO 2.5 powders to Sr 2 Mn 2 O 5−x F 1+x resulted in the oxidation of Mn cations to a mixed Mn 3+ /Mn 4+ valence, which suggests F incorporation into O vacancies was the dominant mechanism [26]. Fluorination of epitaxial La 0.74 Sr 0.26 MnO 3−δ films was found to occur through a combination of F insertion of anion vacancies and substitution for O, resulting in a decrease of the Curie temperature [28]. Our recent study of fluorination mechanisms in epitaxial SrMnO 2.5 films revealed F substitution for O as the dominant means of fluorine incorporation.…”

Synergistic Bulk and Surface Engineering for Expeditious and Durable Reversible Protonic Ceramic Electrochemical Cells Air Electrode

“…Similar experimental results have also been reported in other studies. [37,38] As discussed above, the intrinsic oxygen chemical bonds also contribute a lot in achieving outstanding ORR/OER catalytic performance. Considering the importance of oxygen vacancies concentration in air electrode materials, thermogravimetric (TG) analysis was carried out to determine the oxygen nonstoichiometry (𝛿) of the samples.…”

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

“…In future studies, we anticipate that this approach can be expanded to other material systems amenable to fluoridation, such as cobaltites, [ 66,67 ] manganites, [ 68–70 ] chromites, [ 71 ] nickelates, [ 72 ] and ruthenates. [ 73 ] While F is particularly useful for topochemical modification of the nature used here, it is also possible that other halides, pnictides, and chalcogenides could be used in a similar manner.…”