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Author Sarkar, R.; Baenitz, M.; Sereni, J.G.; Geibel, C.
Title 29Si NMR study of the heavy fermion system CeRuSi Type Journal Article
Year 2010 Publication Journal of Physics: Conference Series Abbreviated Journal J. Phys. Conf. Ser.
Volume 200 Issue Pages (down) 012173
Keywords Basal planes; Energy scale; Heavy fermion systems; High-T; Kondo temperatures; Local probes; Low energies; NMR studies; Powder spectra; Drops; Silicon
Abstract A recent investigation of the low temperature properties of the paramagnetic heavy fermion system CeRuSi revealed an anomalous decrease of the coefficient C/T below 6 K, indicating a second low energy scale well below the Kondo temperature of about 50 K. We started an investigation of this unusual behavior using the local probe 29Si-NMR. Here a preliminary 29Si field sweep NMR study in the temperature 4.2-200 K is reported. 29Si-NMR powder spectra obtained at 72.9 MHz could be simulated and shift components 29Kab(T) and 29K c(T) were determined. The shift along the basal plane 29Kab(T) shows the expected behavior with a Curie-Weiss dependence at high T merging in a constant value below 15 K. In contrast the shift along the tetragonal axis reveals an anomalous T dependence below 15 K where 29Kc(T) drops by a factor of 2, confirming the presence of a further low T energy scale. We suspect this drop to be related to the anomalous decrease of C/T below 6 K and discuss possible mechanism. © 2010 IOP Publishing Ltd.
Address Divisin Bajas Temperaturas, Centro Atmico Bariloche, Comisin Nacional de Energia Atmica, cc 439, 8400 San Carlos de Bariloche, Argentina
Corporate Author Thesis
Publisher Place of Publication Karlsruhe Editor
Language Summary Language Original Title
Series Editor Series Title International Conference on Magnetism, ICM 2009 Abbreviated Series Title
Series Volume 200 Series Issue SECTION 1 Edition
ISSN 17426588 (ISSN) ISBN Medium
Area Expedition Conference
Notes Conference code: 81773; Export Date: 10 December 2010; Source: Scopus; Art. No.: 012173; doi: 10.1088/1742-6596/200/1/012173; Language of Original Document: English; Correspondence Address: Sarkar, R.; Max-Planck Institute for Chemical Physics of Solids, 01187 Dresden, Germany; email: rajibsarkarsinp@gmail.com; References: Sereni, J.G., J. Phys.: Condens. Matter., , submitted to; Welter, R., (1992) J. Alloys Comput., 189 (1), p. 49; Chevalier, B., (2008) Phys. Rev., 77 (1), p. 014414; Rebelsky, L., (1988) J. Appl.Phys., 63 (8), p. 3405; Kitaoka, Y., (1985) J. Phys. Soc. Japan., 54 (9), p. 3236; Krishna-Murthy, H.R., (1975) Phys. Rev. Lett., 35 (16), p. 1101; Chevalier, B., (2006) Physica, 378-380, p. 795; Kim, J.K., Troyer, M., (1998) Phys. Rev. Letter, 80 (12), p. 2705 Approved no
Call Number BT @ berisso @ Serial 598
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Author Deppe, M.; Caroca-Canales, N.; Sereni, J.G.; Geibel, C.
Title Evidence for a metamagnetic transition in the heavy Fermion system CeTiGe Type Conference Article
Year 2010 Publication Journal of Physics: Conference Series Abbreviated Journal J. Phys.: Conf. Ser.
Volume 200 Issue Pages (down) 012026
Keywords Applied magnetic fields; Canonical systems; Continuous suppression; Critical behavior; Critical fields; DC magnetization; First order; Heavy fermion systems; Higher temperatures; Low temperatures; Metamagnetic; Metamagnetic transitions; Polycrystalline; Cerium; Cerium compounds; Electric resistance; Magnetic field effects; Magnetoresistance; Magnetism
Abstract A recent study of CeTiGe identified this compound as a paramagnetic heavy Fermion system where the full J = 5/2 multiplet is involved in the formation of the ground state. Here we present a preliminary investigation of the dc-magnetization Mdc(H) and of the magnetoresistance ρ(H) of polycrystalline CeTiGe samples in applied magnetic fields up to μ0H = 14 T. The results reveal a pronounced metamagnetic transition at a critical field μ0Hc ≈ 13.5 T at low temperatures, with a step like increase in Mdc(H) of at least 0.6 μB/Ce. The metamagnetic transition leads to a strong decrease in ρ(H). A clear hysteresis in Mdc(H) and ρ(H) indicate that in CeTiGe these metamagnetic features correspond to a true thermodynamic, first order type transition in contrast to the critical behavior observed in the canonical system CeRu2Si2. Measurements at higher temperatures showed a continuous suppression of the metamagnetic transition with increasing T, which vanishes at T ∼ 30 K. © 2010 IOP Publishing Ltd.
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Corporate Author Thesis
Publisher Place of Publication Karlsruhe Editor
Language Summary Language Original Title
Series Editor Series Title International Conference on Magnetism, ICM 2009 Abbreviated Series Title
Series Volume 200 Series Issue SECTION 1 Edition
ISSN 17426588 (ISSN) ISBN Medium
Area Expedition Conference
Notes Conference code: 81773; Export Date: 10 December 2010; Source: Scopus; Art. No.: 012026; doi: 10.1088/1742-6596/200/1/012026; Language of Original Document: English; Correspondence Address: Deppe, M.; Max Planck Institute for Chemical Physics of Solids, D-01187 Dresden, Germany; email: Hicha.Deppe@cpfs.mpg.de; References: Gegenwart, P., Si, Q., Steglich, F., (2008) Nature Phys., 4 (3), p. 186; Sachdev, S., (2008) Nature Phys., 4 (3), p. 173; Blundell, S., (2001) Oxford Master Series in Condensed Matter Physics, , (Oxford University Press); Monthoux, P., Lonzarich, G.G., (2001) Phys. Rev., 63 (5), p. 054529; Morozkin, A.V., Seropegin Yu, D., Leonov, A.V., Sviridov, I.A., Tskhadadze, I.A., Nikitin, S.A., (1998) J. Alloys Comput., 267, pp. 14-15R; Welter, R., Vernière, A., Venturini, G., Malaman, B., (1999) J. Alloys. Compounds, 283 (1-2), p. 54; Deppe, M., Caroca-Canales, N., Hartmann, S., Oeschler, N., Geibel, C., (2009) J. Phys.: Condens. Matter, 21 (20), p. 206001; Hewson, A.C., (1993) The Kondo Problem to Heavy Fermions (Cambridge Studies in Magnetism), 2. , ed D Edwards and D Melville (Cambridge: Cambridge University press); Haen, P., Flouquet, J., Lapierre, F., Lejay, P., Remenyi, G., (1987) J. Low Temp. Phys., 67 (5-6), p. 391; Sakakibara, T., Tayama, T., Matamura, K., Maezawa, K., Onuki, Y., Amitsuka, H., (1995) Phys. Rev., 51 (17), p. 12030; Andreev, A.V., Vejpravov, J., Prokleška, J., Sechovsky, V., (2008) Physica, 403 (5-9), p. 744 Approved no
Call Number BT @ berisso @ Serial 599
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Author Luzuriaga, J.
Title Mean free path in soccer and gases Type Journal Article
Year 2010 Publication European Journal of Physics Abbreviated Journal
Volume 31 Issue 5 Pages (down) 1071-1076
Keywords
Abstract The trajectories of the molecules in an ideal gas and of the ball in a soccer game are compared. The great difference between these motions and some similarities are discussed. This example could be suitable for discussing many concepts in kinetic theory in a way that can be pictured by students for getting a more intuitive understanding. It could be suitable for an introductory course in vacuum techniques or undergraduate courses in kinetic theory of gases. Without going into the slightly harder quantitative results, the analysis presented might be used for introducing some ideas of kinetic theory qualitatively to high school students. © 2010 IOP Publishing Ltd.
Address Centro Atómico Bariloche-CNEA, Instituto Balseiro, UNC, 8400, Bariloche, Argentina
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Notes Export Date: 9 August 2012; Source: Scopus Approved no
Call Number BT @ hernan @ Serial 649
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Author Sereni, J.G.; Gomez Berisso, M.; Canales, N.C.; Deppe, M.; Geibel, C.
Title Tuning ground state degeneracy and quantum criticality in Ce1-xLaxTiGe Type Journal Article
Year 2010 Publication Physica Status Solidi (B) Basic Research Abbreviated Journal Phys. Status Solidi B Basic Res.
Volume 247 Issue 3 Pages (down) 707-709
Keywords
Abstract We have tuned the paramagnetic heavy Fermion (HF) system CeTiGe to a more magnetic state and toward quantum criticality (QC) by partially substituting La for Ce. The induced volume expansion leads to a pronounced decrease of the Kondo temperature (TK), from ≈50 K in pure CeTiGe to less than 4 K at large La content. Since the former value is of the order of the crystal field splitting, while the latter is well below, the systems evolves from a large degeneracy N = 6 Kondo system at x = 0 to a conventional N = 2 Kondo system at x ≥ 0:8. There, the first excited crystal field doublets become apparent in the T dependence of the specific heat CP(T) at an excitation energy DCF ≈ 30 K. The reduction of the degeneracy is expected to enhance the decrease of TK, explaining the strong reduction by more than one order of magnitude observed in this system. The decrease of TK drives the system toward QC as evidenced by a divergence of CP(T)/T and x(T) toward low temperatures in the x = 0:8 sample. © 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
Address Max Planck Institute for Chemical Physics of Solids, 01187 Dresden, Germany
Corporate Author Thesis
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Language Summary Language Original Title
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ISSN 03701972 (ISSN) ISBN Medium
Area Expedition Conference
Notes Export Date: 1 June 2010; Source: Scopus; doi: 10.1002/pssb.200983029; Language of Original Document: English; Correspondence Address: Sereni, J.G.; Low Temperature Laboratory, Centro Atómico Bariloche (CNEA), 8400 S. C. Bariloche, Argentina; email: jsereni@cab.cnea.gov.ar; References: Löhneysen, H.v., Rosch, A., Vojta, M., Wölfle, P., (2007) Rev. Mod. Phys., 79, p. 1015; Welter, R., Venturini, G., Malamann, B., (1992) J. Alloys Compd, 189, p. 49; Deppe, M., Caroca-Canales, N., Hartmann, S., Oeschler, N., Geibel, C., (2009) J. Phys. Condens. Matter, 21, p. 206001; Deppe, M., Caroca-Canales, N., Sereni, J.G., Geibel, C., (2010) J. Phys.:Condens. Matter, , accepted; Stewart, G.R., (2006) Rev. Mod. Phys., 78, p. 743; Schlottmann, P., (1984) Phys. Rev. B, 30, p. 1454; Desgranges, H.U., Rasul, J.W., (1987) Phys. Rev. B, 36, p. 328 Approved no
Call Number BT @ berisso @ Serial 594
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Author Antonio, D.; Dolz, M.I.; Pastoriza, H.
Title Magnetization measurement of single La0.67Ca0.33MnO3 nanotubes in perpendicular magnetic fields using a micromechanical torsional oscillator Type Journal Article
Year 2010 Publication Journal of Magnetism and Magnetic Materials Abbreviated Journal
Volume 322 Issue 5 Pages (down) 488-493
Keywords Manganite nanotubes; Micromachined magnetometers; Shape anisotropy
Abstract Using a silicon micromechanical resonator as a sensitive magnetometer, the authors have studied both experimentally and theoretically the magnetic behavior of two isolated ferromagnetic nanotubes of perovskite La0.67Ca0.33MnO3. The article investigates the specific configuration where a magnetic field H is applied perpendicular to the magnetic easy axis of an isolated nanotube characterized by an uniaxial anisotropy constant K. In this situation, the magnetization M reduces the effective elastic constant kM of the resonator. This softening of the mechanical system is opposed to the hardening effect of M observed in a previous work, where H was applied parallel to the easy axis. Moreover, in this magnetic field configuration two distinct magnetization regimes are manifested, depending on the magnitude of H. For H[not double greater-than sign]2K/M the magnetization is almost parallel to the applied magnetic field and for H[double less-than sign]2K/M it is almost parallel to the easy axis of the nanotube. At a certain value of H there is a sharp transition
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ISSN 0304-8853 ISBN Medium
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Call Number BT @ hernan @ 13272 Serial 585
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Author Conte, V.; Giordano, J.L.; Zarate, J.J.; Luzuriaga, J.
Title Superconducting Devices for Radioastronomy; First Steps in Chile: SNS-junction Fabrication Type Conference Article
Year 2010 Publication Abbreviated Journal
Volume 1 Issue Pages (down) 424-427
Keywords
Abstract We present results of the microfabrication of Josephson Junctions (JJs) of Superconductor-Normal-superconductor (SNS) type, as a first step in the acquisition of the know-how of superconducting devices applied to radioastronomy. A twojunction SQUID was built using a Nb/Al bilayer deposited on a Si wafer. The procedure needs only one mask and a single UV exposure (i.e., one photolithography step). We show the micrograph and the observed non linear characteristic I-V curve at 4K of the first device fabricated in the framework of ALMA Grant 31090010.
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Area Expedition Conference Twenty-First International Symposium on Space Terahertz Technology
Notes Approved no
Call Number BT @ pedrazp @ Serial 736
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Author Haberkorn, N.; Lovey, F. C.; Condó, A. M.; Guimpel, J
Title Development and characterization of shape memory Cu-Zn-Al thin films Type Journal Article
Year 2010 Publication Materials Science and Engineering B: Solid-State Materials for Advanced Technology Abbreviated Journal
Volume 170 Issue 1-3 Pages (down) 5-8
Keywords
Abstract Ternary Cu-Zn-Al alloys show good shape memory properties with narrow hysteresis and a wide range of martensitic transformation temperature (Ms), depending on the alloy composition. Thin films of Cu-Zn-Al with shape memory effect were grown for the first time using a new procedure. First Cu-Al thin films were obtained by DC sputtering on Si (1 0 0) substrates at room temperature, and second, the Cu-Al films were encapsulated and annealed in the presence of a Cu-Zn-Al bulk reference in order to fix a Zn vapour pressure. In this way a controlled amount of Zn is transported from the bulk reference into the film, in such a way that the Ms of the film becomes nearly the same as the bulk reference. The structures and microstructures of the as grown films were analysed by X-ray diffraction and transmission electron microscopy. The martensitic transformation temperature was determined by resistivity measurements.
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Call Number BT @ hernan @ Serial 603
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Author Gil, D.M.; Navarro, M.C.; Lagarrigue, M.C.; Guimpel, J.; Carbonio, R.E.; Gómez, M.I.
Title Synthesis and structural characterization of perovskite YFeO3 by thermal decomposition of a cyano complex precursor, Y[Fe(CN)6]·4H2O} Type Journal Article
Year 2010 Publication Journal of Thermal Analysis and Calorimetry Abbreviated Journal
Volume Issue Pages (down) 1-8
Keywords
Abstract The thermal decomposition of Y[Fe(CN)6]·4H2O has been studied in order to investigate the formation of the multi-ferroic oxide YFeO3. The starting material (Y[Fe(CN)6]·4H2O) and the decomposition products were characterized by IR spectroscopy, thermal analysis, X-ray powder diffraction (PXRD), and scanning electron microscopy. Metastable YFeO3 with hexagonal structure, space group P63/mmc, was obtained by thermal decomposition of Y[Fe(CN)6]·4H2O at 600 °C in air. Orthorhombic YFeO3 was obtained by the same method at T ≥ 800 °C in air. The crystal structure of orthorhombic YFeO3 was refined by Rietveld analysis using PXRD data. We found that it was slightly deficient in Y3+, which is in agreement with the small amount of Y2O3 found as impurity in the sample. The formula of the orthorhombic phase is Y0.986FeO3
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ISSN 13886150 ISBN Medium
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Call Number BT @ hernan @ Serial 601
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