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Franco, D. G., R. E. Carbonio, E. E. Kaul, and G. Nieva. "Tailoring the ground state of the ferrimagnet La2Ni(Ni1/3Sb2/3)O6." Journal of Magnetism and Magnetic Materials 346 (2013): 196–202.
Abstract: We report on the magnetic and structural properties of La2Ni(Ni1/3Sb2/3)O6 in polycrystal, single crystal and thin film samples. We found that this material is a ferrimagnet ( T c ≈ 100 K ) which possesses a very distinctive and uncommon feature in its virgin curve of the hysteresis loops. We observe that bellow 20 K it lies outside the hysteresis cycle, and this feature was found to be an indication of a microscopically irreversible process possibly involving the interplay of competing antiferromagnetic interactions that hinder the initial movement of domain walls. This initial magnetic state is overcome by applying a temperature dependent characteristic field. Above this field, an isothermal magnetic demagnetization of the samples yield a ground state different from the initial thermally demagnetized one.
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Franco, D. G., R. E. Carbonio, and G. Nieva. "Synthesis and structural and magnetic characterization of the frustrated magnetic system La2Ni4/3−xCoxSb2/3O6." Journal of Solid State Chemistry 207 (2013): 69–79.
Abstract: 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 30 K 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.
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Franco, D. G., V. C. Fuertes, M. C. Blanco, M. T. Fernández-Díaz, R. D. Sánchez, and R. E. Carbonio. "Synthesis, structure and magnetic properties of La3Co2SbO9: A double perovskite with competing antiferromagnetic and ferromagnetic interactions." Journal of Solid State Chemistry 194 (2012): 385–391.
Abstract: The synthesis, structural characterization, and magnetic properties of La3Co2SbO9 double perovskite are reported. The crystal structure has been refined by X-ray and neutron powder diffraction data in the monoclinic space group P21/n. Co2+ and Sb5+ have the maximum order allowed for the La3Co2SbO9 stoichiometry. Rietveld refinements of powder neutron diffraction data show that at room temperature the cell parameters are a=5.6274(2) Å, b=5.6842(2) Å, c=7.9748(2) Å and β=89.999(3)°. Magnetization measurements indicate the presence of ferromagnetic correlations with TC=55 K attributed to the exchange interactions for non-linear Co2+–O–Sb5+–O–Co2+ paths. The effective magnetic moment obtained experimentally is μexp=4.38 μB (per mol Co2+), between the theoretical one for spin only (3.87 μB) and spin-orbit value (6.63 μB), indicating partially unquenched contribution. The low magnetization value at high magnetic field and low temperature (1 μB/f.u., 5 T and 5 K) and the difference between ZFC and FC magnetization curves (at 5 kOe) indicate that the ferromagnetism do not reach a long range order and that the material has an important magnetic frustration.
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Sereni, J. G., J. Roberts, F. Gastaldo, M. Gómez Berisso, and M. Giovannini. "Shastry-Sutherland phase formation in magnetically frustrated Ce2Pd2In1-xSnx alloys." Materials Today: Proceedings 14 (2019): 80–83.
Abstract: Taking profit that the ternary indides Ce2+εPd2-εIn form two branches of solid solutions allowing to access to ferromagnetic (FM, ε > 0) or anti-ferromagnetic (AFM, ε < 0) ground states depending on the relative Ce/Pd concentration 'ε' , we have tested the possibility of a Shastry-Sutherland phase formation by electron doping the trivalent In lattice with tetravalent Sn. Starting from the AFM, ε < 0 side provides the lowest electron concentration conditions increasing the sensitivity to electron doping. For such a purpose low temperature thermal and magnetic properties were investigated on Ce2+εPd2-εIn1-xSnx alloys within the 0 ≤ x ≤ 0.6 range of concentration.
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