Synthesis and structural and magnetic characterization of the frustrated magnetic system La2Ni4/3−xCoxSb2/3O6

• Published in: Journal of solid state chemistry Vol. 207; pp. 69 - 79
• Main Authors: Franco, D.G., Carbonio, R.E., Nieva, G.
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier Inc 01.11.2013; Elsevier
• Subjects: Coercive force; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Condensed matter: structure, mechanical and thermal properties; Double perovskites; Exact sciences and technology; Ferrimagnetics; Ferrimagnetism; Hysteresis loops; Magnetic frustration; Magnetic properties and materials; Magnetization curves; Neutron diffraction; Neutron diffraction and scattering; Perovskites; Physics; Rietveld refinement; Single-crystal and powder diffraction; Solid state; Spin glass; Structure of solids and liquids; crystallography; Structure of specific crystalline solids; Studies of specific magnetic materials; Synthesis; Thermal evolution; Rietveld refinement; Double perovskites; Ferrimagnetism; Neutron diffraction; Magnetic frustration; Rietveld method; Spin glasses; Space groups; Magnetic cluster; Composition effect; Magnetic hysteresis; Ferrimagnetic materials; Hysteresis loop; Solid state; Powder pattern; Transition elements; Coercive force; Crystallographic site; Saturation magnetization; Crystal structure
• ISSN: 0022-4596; 1095-726X
• DOI: 10.1016/j.jssc.2013.09.011

We report the synthesis of double perovskites La2Ni4/3−xCoxSb2/3O6 with x=0, 1/3, 2/3 and 1 by a solid state method. Rietveld refinements of X-ray and neutron powder diffraction data show that all samples crystallize in space group P21/n, with almost perfect occupation of the 2d octahedral site with the transition metals, while all Sb5+ are randomly distributed in a 2c octahedral site. The saturation magnetization in hysteresis loops indicates that the samples are ferrimagnetic throughout all the series. Virgin magnetization curves lie outside hysteresis loops at low temperatures and thermal evolution of Hm – defined as the inflection point of these curves – follows the de Almeida–Thouless dependence for x≠0. This spin glass like behavior below 30K is also supported by thermal evolution of the coercivity, which follows an exponential law typical of magnetic clusters, not found in the pure Ni2+ perovskite, x=0 extreme. [Display omitted] •We synthesized new double perovskites: La2Ni4/3−xCoxSbO6 (x=1/3, 2/3, 1).•The cations occupying octahedral sites are highly ordered in all samples.•Magnetic transition occurs as a consequence of superexchange paths.•Frustration is found and attributed to competition between different interactions.