Optimization of Pr_0.9Ca_0.1MnO₃ thin films with varying in-situ oxygen annealing treatments

¹ Wihuri Physical Laboratory, Department of Physics and Astronomy, University of Turku, FI-20014 Turku, Finland
² The National Graduate School in Material Physics (NGSMP), Helsinki, Finland

^a e-mail: tomi.elovaara@utu.fi

Abstract

The influence of in situ oxygen annealings on narrow electronic bandwidth Pr_0.9Ca_0.1MnO₃ films are investigated in the complex phase separation region. Measurements by x-ray diffractometry and SQUID magnetometry reveal that relatively high deposition temperature at 700 °C relaxes the lattice by twin boundaries while the lower deposition temperature at 500 °C with higher post-annealing temperature of 700 °C relaxes the substrate induced strain via oxygen absorption and makes the film structure more homogeneous. This behaviour is clearly supported by the decrease of ferromagnetic ordering due to decrease of Mn³⁺ ions in films oxygen annealed at high temperatures and this phenomenon is widely discussed with the models of double-exchange interaction, trapping of carriers in the oxygen vacancies and formation of magnetic polarons. The results show unambiguously that because the oxygen content tailors many physical properties dramatically, the annealing treatments are in very important role when optimizing these materials for future applications.