The role of the impurities and oxygen vacancy of SrTiO3 perovskite oxide: ab initio and 57Fe Mossbauer studies

A. M. MUDARRA NAVARRO; C. RODRIGUEZ TORRES; L. ERRICO; K. NOMURA; T.TAKAHASHI

Cartagena

Conferencia; XXXVII International Conference on the applications of the Mossbauer effect (XXXVII ICAME); 2023

Ab initio calculations are performed using the full potential linearized extended plane wave (FP-LAPW) method [1] in the framework of density functional theory (DFT [1, 2]). Considering different vacancy concentrations and distributions in the host, we have investigated the effects of oxygen vacancies on the magnetic and hyperfine properties and the magnetic alignment of impurities, such as on SnO2 doped with Fe and Co [3]. In this work, we present theoretical and experimental studies of the magnetic and hyperfine properties of (Fe, Sn) co-doped perovskite oxide, SrTiO3. In our calculations, Fe and Sn impurities promote the creation of oxygen vacancies (preferably close to Fe atoms but far from Sn atoms), sharing oxygen vacancies with antiparallel spin orientation. It was predicted ab initio to form a ferrimagnetic entity, forming a pair of magnetic impurities. The calculations were then compared with the experimental results. SrTiO3 samples co-doped with 1.0% enriched 57Fe and 0–10% Sn were obtained by sol-gel and pyrolysis. We compared the results of Mössbauer spectroscopy (MS) and sample magnetometry (VSM). We were able to identify the hyperfine interactions observed by MS and unambiguously characterize the local structure around the Fe atom. Finally, based on theoretical results for the lowest energy Fe–Fe and Fe–Sn magnetic configurations, the experimental behavior of saturation magnetization obtained by VSM measurements can be understood and reproduced as a function of Sn concentration (similar to the magnetic moment per magnetic atom) Reference[1] Hohenberg P.; Kohn, W. Inhomogeneous Electron Gas. Phys. Rev.1964, 136, B864−B871[2] Kohn, W.; Sham, L. J. Self-Consistent Equations Including Exchange and Correlation Effects. Phys.Rev.1965, 140, A1133−A1138.[3] A.M. Mudarra Navarro et al., Materials Chemistry and Physics, 257 (2021) 123822