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Author Cecilia Blanco, M.; De Paoli, J.M.; Ceppi, S.; Tirao, G.; Nassif, V.M.; Guimpel, J.; Carbonio, R.E. url  openurl
  Title Synthesis, structural characterization and magnetic properties of the monoclinic ordered double perovskites BaLaMSbO6, with M = Mn, Co and Ni Type Journal Article
  Year 2014 Publication Journal of Alloys and Compounds Abbreviated Journal  
  Volume 606 Issue Pages 139-148  
  Keywords Double perovskites; Magnetic properties; X-ray emission spectroscopy; Neutron powder diffraction  
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  Series Volume Series Issue Edition  
  ISSN 0925-8388 ISBN Medium  
  Area Expedition Conference  
  Notes Approved no  
  Call Number BT @ jguimpel @ Serial 681  
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Author Franco, D.G.; Carbonio, R.E.; Kaul, E.E.; Nieva, G. doi  openurl
  Title Tailoring the ground state of the ferrimagnet La2Ni(Ni1/3Sb2/3)O6 Type Journal Article
  Year 2013 Publication Journal of Magnetism and Magnetic Materials Abbreviated Journal J. Magn. Magn. Mater.  
  Volume 346 Issue Pages 196-202  
  Keywords Ferrimagnetic; Double perovskite; Magnetic frustration; Superexchange and super-superexchange interaction; Magnetic oxide  
  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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  Series Volume Series Issue Edition  
  ISSN 0304-8853 ISBN Medium  
  Area Expedition Conference  
  Notes Approved no  
  Call Number BT @ pedrazp @ Serial 666  
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Author Franco, D.G.; Carbonio, R.E.; Nieva, G. doi  openurl
  Title Change in the Magnetic Domain Alignment Process at the Onset of a Frustrated Magnetic State in Ferrimagnetic La2Ni(Ni1/3Sb2/3)O6 Double Perovskite Type Journal Article
  Year 2013 Publication IEEE Transactions on Magnetics Abbreviated Journal IEEE Trans. Magn.  
  Volume 49 Issue 8 Pages 4656-4659  
  Keywords coercive force; exchange interactions (electron); ferrimagnetic materials; frustration; magnetic domain walls; magnetic hysteresis; magnetic transitions; LaNi(Ni0.33Sb0.67)O6; applied magnetic field; coercive field; domain wall pinning; ferrimagnetic double perovskite; ferrimagnetic order transition; frustrated magnetic state; hysteresis data; low temperature regime; magnetic domain alignment process; magnetic exchange interactions; magnetization hysteresis loops; temperature dependence; Magnetic domain walls; Magnetic domains; Magnetic hysteresis; Magnetization; Nickel; Temperature distribution; Temperature measurement; Ferrimagnetic materials; magnetic analysis; magnetic domain walls; magnetic hysteresis  
  Abstract We have performed a combined study of magnetization hysteresis loops and time dependence of the magnetization in a broad temperature range for the ferrimagnetic La2Ni(Ni1/3Sb2/3)O6 double perovskite. This material has a ferrimagnetic order transition at ~100 K and at lower temperatures (~20 K) shows the signature of a frustrated state due to the presence of two competing magnetic exchange interactions. The temperature dependence of the coercive field shows an important upturn below the point where the frustrated state sets in. The use of hysteresis data, magnetization versus applied magnetic field, together with the magnetization versus time data provides a unique opportunity to distinguish between different scenarios for the low temperature regime. From our analysis, a strong domain wall pinning results in the best scenario for the low temperature regime. For temperatures larger than 20 K, the adequate scenario seems to correspond to a weak domain wall pinning.  
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  Series Volume Series Issue Edition  
  ISSN 0018-9464 ISBN Medium  
  Area Expedition Conference  
  Notes Approved no  
  Call Number BT @ pedrazp @ Serial 668  
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Author Franco, D.G.; Carbonio, R.E.; Nieva, G. doi  openurl
  Title Magnetic Properties of the Double Perovskites LaPbMSbO6 (M = Mn, Co, and Ni) Type Journal Article
  Year 2013 Publication IEEE Transactions on Magnetics Abbreviated Journal IEEE Trans. Magn.  
  Volume 49 Issue 8 Pages 4594-4597  
  Keywords X-ray diffraction; cobalt compounds; lanthanum compounds; lead compounds; magnetisation; manganese compounds; nickel compounds; paramagnetic-antiferromagnetic transitions; space groups; superexchange interactions; LaPbCoSbO6; LaPbMnSbO6; LaPbNiSbO6; M2+ distribution; Rietveld analysis; Sb5+ distribution; X-ray powder diffraction pattern; antiferromagnetic coupling; antiferromagnetic transition; aqueous synthetic route; disorder; double perovskites; ferrimagnetic characteristics; interaction paths; magnetic ions; magnetic properties; monoclinic crystals; octahedral sites; polycrystals; space group P2 1/n; super-superexchange paths; Ions; Magnetic properties; Magnetization; Manganese; Nickel; Temperature measurement; X-ray diffraction; Antiferromagnetic materials; transition metal compounds  
  Abstract New double perovskites LaPbMSbO6, where M2+ = Mn2+, Co2+, and Ni2+, were synthesized as polycrystals by an aqueous synthetic route at temperatures below 1000 °C. All samples are monoclinic, space group P21/n, as it is observed from Rietveld analysis of X-ray powder diffraction patterns. The distribution of M2+ and Sb5+ among the two octahedral sites have 3% of disorder for M2+ = Ni2+, whereas for M2+ = Mn2+ and Co2+ less disorder is found. The three samples have an antiferromagnetic transition, due to the antiferromagnetic coupling between M2 + through super-superexchange paths M2+-O2--Sb5+-O2--M2+. Transition temperatures are low: 8, 10 and 17 K for Mn2+, Co2+, and Ni2 + respectively, as a consequence of the relatively long distances between the magnetic ions M2+. Besides, for LaPbMnSbO6 a small transition at 45 K was found, with ferrimagnetic characteristics, possibly as a consequence of a small disorder between Mn2+ and Sb5+. This disorder would give additional and shorter interaction paths: superexchange Mn2+-O2--Mn2+.  
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  Series Editor Series Title Abbreviated Series Title  
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  ISSN 0018-9464 ISBN Medium  
  Area Expedition Conference  
  Notes Approved no  
  Call Number BT @ pedrazp @ Serial 669  
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Author Franco, D.G.; Carbonio, R.E.; Nieva, G. url  doi
openurl 
  Title Synthesis and structural and magnetic characterization of the frustrated magnetic system La2Ni4/3−xCoxSb2/3O6 Type Journal Article
  Year 2013 Publication Journal of Solid State Chemistry Abbreviated Journal J. Solid State Chem.  
  Volume 207 Issue Pages 69-79  
  Keywords Double perovskites; Neutron diffraction; Rietveld refinement; Ferrimagnetism; Magnetic frustration  
  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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  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 0022-4596 ISBN Medium  
  Area Expedition Conference  
  Notes Approved no  
  Call Number BT @ pedrazp @ Serial 670  
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Author Franco, D.G.; Fuertes, V.C.; Blanco, M.C.; Fernández-Díaz, M.T.; Sánchez, R.D.; Carbonio, R.E. url  doi
openurl 
  Title Synthesis, structure and magnetic properties of La3Co2SbO9: A double perovskite with competing antiferromagnetic and ferromagnetic interactions Type Journal Article
  Year 2012 Publication Journal of Solid State Chemistry Abbreviated Journal J. Solid State Chem.  
  Volume 194 Issue Pages 385-391  
  Keywords La3Co2SbO9; Double perovskite; Powder neutron diffraction; Rietveld refinement; Ferromagnetic; Magnetic frustration  
  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) Ã…, b=5.6842(2) Ã…, c=7.9748(2) Ã… 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.  
  Address  
  Corporate Author Thesis  
  Publisher Place of Publication Editor  
  Language Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 0022-4596 ISBN Medium  
  Area Expedition Conference  
  Notes Approved no  
  Call Number BT @ pedrazp @ Serial 671  
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