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Author (up) Franco, D.G.; Geibel, C.
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.
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 2469-9950 ISBN Medium
Area Expedition Conference
Notes Approved no
Call Number BT @ pedrazp @ Serial 877
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Author (up) Franco, D.G.; Sarmiento-Chavez, A.; Schenone, N.; Allcca, A.E.L.; Berisso, M.G.; Fasano, Y.; Guimpel, J.
Title Characterization of the Nb-B Superlattice System Type Journal Article
Year 2016 Publication Physica C: Superconductivity and its Applications Abbreviated Journal
Volume 531 Issue Pages 93-97
Keywords Superlattice; Superconductivity; Transition Edge Sensors
Abstract Abstract

We study the growth, stacking and superconducting properties of Nb and B thin films and superlattices. The interest in these resides in their possible use in transition edge neutron sensors. The samples were grown by magnetron sputtering over Si (100) substrates. The X-ray diffraction patterns for all Nb containing samples show a Nb (110) preferential orientation. From the low-angle X-ray reflectivity we obtain information on the superlattice structure. The superconducting transition temperatures of the superlattices, obtained from the temperature dependence of the magnetization, are higher than those of single Nb films of similar thickness. The temperature dependence of the perpendicular and parallel upper critical fields indicate that the superlattices behave as an array of decoupled superconducting Nb layers.
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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 0921-4534 ISBN Medium
Area Expedition Conference
Notes Approved no
Call Number BT @ jguimpel @ Serial 743
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Author (up) Gil, D.M.; Nieva, G.; Franco, D.G.; Gómez, M.I.; Carbonio, R.E.
Title Lead nitroprusside: A new precursor for the synthesis of the multiferroic Pb2Fe2O5, an anion-deficient perovskite Type Journal Article
Year 2013 Publication Materials Chemistry and Physics Abbreviated Journal Mater. Chem. Phys.
Volume 141 Issue 1 Pages 355-361
Keywords Inorganic compounds; Magnetic materials; Powder diffraction; Thermogravimetric analysis (TGA); Magnetic properties
Abstract In order to investigate the formation of multiferroic oxide Pb2Fe2O5, the thermal decomposition of Pb[Fe(CN)5NO] has been studied. The complex precursor and the thermal decomposition products were characterized by IR and Raman spectroscopy, thermal analysis, powder X-ray diffraction (PXRD), scanning electron microscopy and magnetic measurements. The crystal structure of Pb[Fe(CN)5NO] was refined by Rietveld analysis. It crystallizes in the orthorhombic system, space group Pnma. The thermal decomposition in air produces highly pure Pb2Fe2O5 as final product. This oxide is an anion deficient perovskite with an incommensurate superstructure. The magnetic measurements confirm that Pb2Fe2O5 shows a weak ferromagnetic signal probably due to disorder in the perfect antiferromagnetic structure or spin canting. The estimated ordering temperature from the fit of a phenomenological model was 520 K. The SEM images reveal that the thermal decomposition of Pb[Fe(CN)5NO] produces Pb2Fe2O5 with small particle size.
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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 0254-0584 ISBN Medium
Area Expedition Conference
Notes Approved no
Call Number BT @ pedrazp @ Serial 667
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Author (up) Haberkorn, N.; Larregola, S.; Franco, D.; Nieva, G.
Title Inhomogeneous ferrimagnetic-like behavior in Gd2/3Ca1/3MnO3 single crystals Type Journal Article
Year 2009 Publication JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS Abbreviated Journal
Volume 321 Issue 9 Pages 1133-1136
Keywords
Abstract We present a study of the magnetic properties of Gd2/3Ca1/3MnO3 single crystals at low temperatures, showing that this material behaves as an inhomogeneous ferrimagnet. In addition to small saturation magnetization at 5 K, we have found history dependent effects in the magnetization and the presence of exchange bias. These features are compatible with microscopic phase separation in the clean Gd2/3Ca1/3MnO3 system studied. (C) 2008 Elsevier B.V. All rights reserved.
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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 0304-8853 ISBN Medium
Area Expedition Conference
Notes ISI:000264170500007 Approved no
Call Number BT @ hernan @ Serial 194
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Author (up) Nikitin, S.E.; Franco, D.G.; Kwon, J.; Bewley, R.; Podlesnyak, A.; Hoser, A.; Koza, M.M.; Geibel, C.; Stockert, O.
Title Gradual pressure-induced enhancement of magnon excitations in CeCoSi Type Journal Article
Year 2020 Publication Physical Review B Abbreviated Journal Phys. Rev. B
Volume 101 Issue Pages 214426
Keywords
Abstract CeCoSi is an intermetallic antiferromagnet with a very unusual temperature-pressure phase diagram: at ambient pressure it orders below

TN=8.8K, while application of hydrostatic pressure induces a new magnetically ordered phase with exceptionally high transition temperature of ∼40K

at 1.5 GPa. We studied the magnetic properties and the pressure-induced magnetic phase of CeCoSi by means of elastic and inelastic neutron scattering (INS) and heat capacity measurements. At ambient pressure CeCoSi orders into a simple commensurate AFM structure with a reduced ordered moment of only

mCe=0.37(6)μB.Specific heat and low-energy INS indicate a significant gap in the low-energy magnon excitation spectrum in the antiferromagnetic phase, with the CEF excitations located above 10 meV. Hydrostatic pressure gradually shifts the energy of the magnon band towards higher energies and the temperature dependence of the magnons measured at 1.5 GPa is consistent with the phase diagram. Moreover, the CEF excitations are also drastically modified under pressure.
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 2469-9950 ISBN Medium
Area Expedition Conference
Notes Approved no
Call Number BT @ pedrazp @ Serial 863
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