Structural and magnetic properties of the La{sub 2−x}Ca{sub x}CoIrO{sub 6} double perovskite series

Journal Article · Thu Jan 15 00:00:00 EST 2015 · Journal of Solid State Chemistry

DOI:https://doi.org/10.1016/J.JSSC.2014.10.019· OSTI ID:22443521

Coutrim, L. T. ^[1]; Freitas, D. C.; Fontes, M. B.; Baggio-Saitovitch, E.; Bittar, E. M. ^[2]; Granado, E.; Pagliuso, P. G. ^[3]

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1. Instituto de Física, Universidade Federal de Goiás, 74001-970 Goiânia, GO (Brazil)
2. Centro Brasileiro de Pesquisas Físicas, Rua Dr. Xavier Sigaud 150, 22290-180 Rio de Janeiro, RJ (Brazil)
3. Instituto de Física “Gleb Wataghin”, UNICAMP, 13083-859 Campinas, SP (Brazil)

Polycrystalline samples of the series La{sub 2−x}Ca{sub x}CoIrO{sub 6} (0≤x≤1.2) have been synthesized and its structural and magnetic properties were investigated using experiments of X-ray powder diffraction, temperature dependent magnetic susceptibility and magnetization as a function of applied magnetic field. All grown polycrystalline compounds form in a monoclinic structure (space group P2{sub 1}/n) with a partially ordered distribution of transition metal cations Co/Ir over the six-coordinate sites. Our results indicate variation of the magnetic interactions between Co and Ir magnetic sublattices possibly due to valence changes of the transition metals, induced by doping. The undoped La{sub 2}CoIrO{sub 6} presents magnetic ordering at ∼97K, while for Ca-doped compounds a decrease of net magnetization and ordering temperatures was observed. For x=0.2 and 0.5 the emergence of a second magnetic interaction, due to the presence of high spin Co{sup 3+}, becomes evident. Interestingly, for x=0.8 the large effective magnetic moment indicates strong orbital contribution and spin-orbit coupling and/or the presence of Co{sup 4+} in high spin state. - Graphical abstract: Field cooling M vs.T curves for La{sub 2−x}Ca{sub x}CoIrO{sub 6} shows the suppression of magnetism with increasing La content. Zero field cooled curves indicate a second magnetic phase induced by the appearance of Co{sup 3+}. - Highlights: • Novel double perovskite series La{sub 2−x}Ca{sub x}CoIrO{sub 6} were synthesized by solid state reaction. • La{sup 3+} to Ca{sup 2+} substitution leads to Co valence and possibly spin state changes. • For some doped compounds, the emergence of a second magnetic phase, due to the presence of high spin Co{sup 3+}, becomes evident. • Physical properties of each compound can be well correlated to the electronic and magnetic evolution of the system.

• OSTI ID: 22443521
• Journal Information: Journal of Solid State Chemistry, Vol. 221; Other Information: Copyright (c) 2014 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved.; Country of input: International Atomic Energy Agency (IAEA); ISSN 0022-4596
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
CALCIUM IONS
CATIONS
COBALT
COBALT IONS
DOPED MATERIALS
HIGH SPIN STATES
INTERACTIONS
IRIDIUM
LANTHANUM IONS
L-S COUPLING
MAGNETIC FIELDS
MAGNETIC MOMENTS
MAGNETIC SUSCEPTIBILITY
MAGNETIZATION
MONOCLINIC LATTICES
PEROVSKITE
POLYCRYSTALS
SPACE GROUPS
SPIN
X-RAY DIFFRACTION