Structural, electronic and magnetic properties of the series of double perovskites (Ca,Sr)2−xLaxFeIrO6

• Published in: Journal of solid state chemistry 2014-04, Vol.212, p.23-29
• Main Authors: Bufaiçal, L., Adriano, C., Lora-Serrano, R., Duque, J.G.S., Mendonça-Ferreira, L., Rojas-Ayala, C., Baggio-Saitovitch, E., Bittar, E.M., Pagliuso, P.G.
• Format: Article
• Language: English
• Subjects: Antiferromagnetism; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Condensed matter: structure, mechanical and thermal properties; Double perovskite; Exact sciences and technology; Ferrimagnetics; Ferrimagnetism; Magnetic properties and materials; Physics; Structure of solids and liquids; crystallography; Structure of specific crystalline solids; Studies of specific magnetic materials
• ISSN: 0022-4596; 1095-726X
• DOI: 10.1016/j.jssc.2014.01.007

Polycrystalline samples of the series of double perovskites Sr2−xLaxFeIrO6 were synthesized. Their structural, electronic and magnetic properties were investigated by X-ray powder diffraction, Mössbauer spectroscopy, magnetic susceptibility, heat capacity and electrical resistivity experiments. The compounds crystallize in a monoclinic structure and were fitted in space group P21/n, with a significant degree of Fe/Ir cationic disorder. As in Ca2−xLaxFeIrO6 the Sr-based system seems to evolve from an antiferromagnetic ground state for the end members (x=0.0 and x=2.0) to a ferrimagnetic order in the intermediate regions (x~1). Since Mössbauer spectra indicate that Fe valence remains 3+ with doping, this tendency of change in the nature of the microscopic interaction could be attributed to Ir valence changes, induced by La3+ electrical doping. Upon comparing both Ca and Sr series, Sr2−xLaxFeIrO6 is more structurally homogenous and presents higher magnetization and transition temperatures. Magnetic susceptibility measurements at high temperatures on Sr1.2La0.8FeIrO6 indicate a very high ferrimagnetic Curie temperature TC~700K. For the Sr2FeIrO6 compound, electrical resistivity experiments under applied pressure suggest that this material might be a Mott insulator. The Weiss constant as a function of La doping for the (Ca,Sr)2−xLaxFeIrO6 series, indicating changes in Fe–Ir magnetic coupling on both families. [Display omitted] •The double perovskite series (Ca,Sr)2−xLaxFeIrO6 were synthesized.•Changes in the Fe-Ir magnetic coupling due to La doping on both series.•Evidence of high TC on Sr1.2La0.8FeIrO6.•Indication of Mott insulator behavior on Sr2FeIrO6.