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Author Franco, D.G.; Geibel, C. url  doi
openurl 
  Title Synthesis and study of the chiral magnetic system EuIr2P2 Type Journal Article
  Year 2021 Publication Physical Review B Abbreviated Journal Phys. Rev. B  
  Volume 104 Issue Pages 054416  
  Keywords Frustrated magnetism; Antiferromagnets; Specific heat; X-ray diffraction  
  Abstract Chiral materials, where no improper symmetry operations such as inversion are resent, are systems prone to the appearance of a skyrmion lattice. Recently it has been shown theoretically that not only ferromagnets (FMs) but also antiferromagnets (AFMs) can host such kind of phases. In this work we study a new candidate for AFM skyrmions, EuIr2P2, by means of magnetization and specific heat measurements on poly and single crystals. X-ray diffraction confirms a trigonal chiral crystal structure, where europium ions form helices along the c direction. In spite of predominantly FM interactions, Eu2+ ions order antiferromagnetically at

TN1=5 K in what seems to be an incommensurate amplitude-modulated magnetic state where the moments are oriented mainly along the c direction. A second magnetic transition takes place at TN2=2.9 K, involving the ordering of an in-plane component of the Eu moment likely resulting in an equal-moment structure. Specific heat data show a tail above TN1. Accordingly the magnetic entropy at

TN1 is strongly reduced in comparison to the expected Rln8 value. This evidences a significant amount of frustration. A simple analysis based on a Heisenberg model indicates that the observed properties imply the presence of several relevant interactions, with competing FM and AFM ones resulting in frustration. Thus

EuIr2P2 is a new interesting magnetic system, where chirality and frustration might result in unconventional magnetic textures.
 
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  ISSN 2469-9950 ISBN Medium  
  Area Expedition Conference  
  Notes Approved no  
  Call Number BT @ pedrazp @ Serial 877  
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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 Volume Series Issue Edition  
  ISSN 0018-9464 ISBN Medium  
  Area Expedition Conference  
  Notes Approved no  
  Call Number BT @ pedrazp @ Serial 669  
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Author Gil, D.M.; Navarro, M.C.; Lagarrigue, M.C.; Guimpel, J.; Carbonio, R.E.; Gómez, M.I. url  openurl
  Title Crystal structure refinement, spectroscopic study and magnetic properties of yttrium hexacyanoferrate (III) Type Journal Article
  Year 2011 Publication Journal of Molecular Structure Abbreviated Journal  
  Volume 1003 Issue 1-3 Pages 129-133  
  Keywords Hexacyanoferrate (III); Powder X-ray diffraction; Rietveld analysis; Infrared spectroscopy; Thermal analysis  
  Abstract Y[Fe(CN)6]·4H2O has been synthesized and characterized. The crystal structure was refined by Rietveld analysis using X-ray powder diffraction data. Y[Fe(CN)6]·4H2O crystallizes in the orthorhombic crystal system, space group Cmcm. Y3+ ion is eight-coordinated forming a bicapped distorted trigonal prism YN6O2. Fe3+ ion is six-coordinated in the form of an irregular octahedra FeC6 group and cyanide linkages between YN6O2 and FeC6 groups build an infinite polymeric array. The vibrational spectrum shows two bands corresponding to antisymmetric and symmetric stretching 12C14N in the CN stretching region. These bands are accompanied by four weak isotopic bands at lower frequency due to the presence of 13C and 15N in relative natural abundance. The HOH bending band split into three bands around 1600 cm−1 due to the presence of two kinds of water molecules in the structure. The thermal decomposition has been followed by thermogravimetric and differential thermal analysis, IR spectroscopy and powder XRD. The size and morphology of the complex and its thermal decomposition products were evaluated by scanning electron microscopy. The magnetic measurements confirm that Y[Fe(CN)6]·4H2O shows an antiferromagnetic order at low temperatures.  
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  Series Volume Series Issue Edition  
  ISSN 0022-2860 ISBN Medium  
  Area Expedition Conference  
  Notes Approved no  
  Call Number BT @ jguimpel @ Serial 607  
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Author Sirena, M.; Kaul, E.; Pedreros, M.B.; Rodriguez, C.A.; Guimpel, J.; Steren, L.B. doi  openurl
  Title Structural, magnetic and electrical properties of ferromagnetic/ferroelectric multilayers Type Journal Article
  Year 2011 Publication Journal of Applied Physics Abbreviated Journal J. Appl. Phys.  
  Volume 109 Issue 12 Pages 123920  
  Keywords atomic force microscopy; barium compounds; electrical conductivity; ferroelectric materials; ferromagnetic materials; lanthanum compounds; magnetic multilayers; magnetisation; multiferroics; sputter deposition; strontium compounds; superlattices; texture; tunnelling; X-ray diffraction  
  Abstract The La0.75Sr0.25MnO3 (LSMO)/Ba0.7Sr0.3TiO3 (BSTO) superlattices and bilayers, where LSMO is ferromagnetic and BSTO is ferroelectric, were grown by dc sputtering. X-ray diffraction indicates that the samples present a textured growth with the c axis perpendicular to the substrate. Magnetization measurements show a decrease of the sample’s magnetization for decreasing ferromagnetic thickness. This effect could be related to the presence of biaxial strain and a magnetic dead layer in the samples. Conductive atomic force microscopy indicates that the samples present a total covering of the ferromagnetic layer for a ferroelectric thickness higher than four unit cells. Transport tunneling of the carriers seems to be the preferred conduction mechanism through the ferroelectric layer. These are promising results for the development of multiferroic tunnel junctions.  
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  ISSN ISBN Medium  
  Area Expedition Conference  
  Notes Approved no  
  Call Number BT @ jguimpel @ Serial 606  
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