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

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 ofmore » 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.« less
Authors:
 [1] ; ; ; ;  [2] ; ;  [3] ;  [1]
  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)
Publication Date:
OSTI Identifier:
22443521
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Solid State Chemistry; Journal Volume: 221; Other Information: Copyright (c) 2014 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved.; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
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