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  • 1
    Electronic Resource
    Electronic Resource
    Weak ferromagnetism induced by the external field above TN in GdzCuO4 : 37th Annual conference on magnetism and magnetic materials (1993)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 73 (1993), S. 5710-5712 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A detailed study of the temperature and field dependence of the dc magnetization near the antiferromagnetic (AF) transition in Gd2CuO4 shows the presence of field-induced weak ferromagnetism (WF) well above the Néel temperature TN. ac susceptibility measurements indicate TN=266(3) and 282(3) K, for single crystals and ceramic samples, respectively. The shift of the electron-spin-resonance line of the Gd3+ ions as a function of temperature T, δHr(T), is compared with the static internal field Hi(T), which describes the coupling between the paramagnetic Gd lattice and the WF component of the Cu moments. Both δHr(T) and Hi(T) show that the WF persists up to ≈50 K above TN. The initial susceptibility (for H≤100 G) presents a contribution in excess of the paramagnetism of Gd ions. For T≥TN, it decays as K(T−TN)−1, with K=0.20(3) emu K mol. The relationship between this result and the strong two-dimensional AF correlations in these cuprates is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.353599
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  • 2
    Electronic Resource
    Electronic Resource
    Phase separation as origin of the magnetic anomalies in La0.85Sr0.15CoO3 (2001)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 89 (2001), S. 5606-5609 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The dependence of the ac-magnetic susceptibility of La0.85Sr0.15CoO3 on the annealing temperature used during synthesis is addressed. Such dependence has been previously attributed to compositional inhomogeneities. Nevertheless, the presence of distinct phases with different chemical compositions is excluded after explorations by several techniques. Instead it is proposed that an electronic phase separation takes place in the material, whose state is changed after charge-carrier redistributions due to the thermal history of the samples, analogously to parent manganese-based perovskites. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1365060
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  • 3
    Electronic Resource
    Electronic Resource
    Magnetic order and weak ferromagnetic transition in Gd2CuO4 (2000)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 87 (2000), S. 5911-5913 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The weak ferromagnetic transition of T′-phase Gd2CuO4 single crystals has been studied by dc-magnetization measurements. Weak ferromagnetism is generated in this material by a very slight canting of the Cu moments from a perfect antiferromagnetic structure. This canting enables the inspection of the magnetic state of the Cu sublattice by pure magnetic methods. The critical exponents of the transition are calculated, γ=1.32(2), β=0.34(1). Nevertheless, a rapid evolution of β to a 2D XY behavior is observed below the critical temperature. It is interpreted as evidence of a transition in the 2D system, namely CuO2 planes, that behave as 3D at the critical point due to the effect of the interlayer interaction along the c-axis. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.372564
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  • 4
    Electronic Resource
    Electronic Resource
    Structural and magnetic characterization of Co particles coated with Ag : The 6th joint magnetism and magnetic materials (MMM)-intermag conference (1994)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 76 (1994), S. 6564-6566 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Co fine particles coated with Ag have been synthesized through the microemulsion method in an inert atmosphere. The size of the particles is controlled by the water droplets of the microemulsions. Fine particles prepared by this method, consist of a magnetic core of Co covered by a layer of Ag. Samples containing from 3.3 to 40.5 vol % Co have been prepared. The average size of the particles obtained is in the nanometer range. The magnetic properties were studied by dc magnetization at 77 K and room temperature. The data show a strong dependence of the magnetic properties on the annealing temperature.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.358195
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  • 5
    Electronic Resource
    Electronic Resource
    Dependence of the magnetic properties Gd2−xCexCuO4, 0≤x≤0.15, on their particle size : 38th Annual Conference ion Magnetism and Magnetic Materials (1994)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 75 (1994), S. 6757-6759 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Gd2−xCexCuO4, 0≤x≤0.15, have been synthesized by the solid state reaction, the sol-gel technique and the water-in-oil microemulsion, in order to vary the particle size. The samples have been characterized by x-ray diffraction, photon correlation spectroscopy and transmission electron microscopy. Magnetization and ac susceptibility measurements were performed between 4 and 300 K. The extrapolated linear part of the inverse magnetization shifts to lower temperatures as the particle size decreases. The internal field associated to the WF of the Cu moments diminishes with the particle diameter. Differences between the zero-field-cooling and the field-cooling magnetization curves were observed for T〈TN. These differences depend on the particle size.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.356844
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  • 6
    Electronic Resource
    Electronic Resource
    Magnetic susceptibility studies in Gd2CuO4 below 300 K : The 6th joint magnetism and magnetic materials (MMM)-intermag conference (1994)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 76 (1994), S. 7034-7036 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Measurements of the real (χ') part of the ac magnetic susceptibility have been performed on two polycrystalline Gd2CuO4 samples sintered at different temperatures, 850 °C and 1080 °C in the temperature range 10〈T(K)〈300. Two well-defined maxima have been observed in the temperature dependence of χ'. One, located at about 20 K, that is frequency independent. The second is at about 280 K for the sample annealed at 1080 °C, and it is frequency independent. Instead, for the sample annealed at 850 °C the maximum appears at about 210 K, and it is frequency dependent. These results suggest the existence of magnetic domains, with their coherence lengths being a function of the thermal treatment.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.358080
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  • 7
    Electronic Resource
    Electronic Resource
    Role of the rare-earth on the electrical and magnetic properties of cobalt perovskites (2000)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 87 (2000), S. 5612-5614 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The magnetic and electrical properties of R1−xSrxCoO3 materials (R=La, Pr, Nd, Gd) (0≤x≤0.50) are studied. Rare-earths with angular momentum L≠0 enhance coercive field values. They are maximum for R=Nd (the highest L) and much smaller for Gd and La (L=0). The result is interpreted as the contribution of the L–S coupling in the rare-earth to the magnetic anisotropy of the system. Electrical conductivity is improved with Sr doping, but increases of rare-earth atomic number lead to decreases of conductivity. This is attributed to the increase of lattice distortions, due to the smaller R3+ ionic size, and to the effect of the rare-earth on the spin state of cobalt ions. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.372467
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  • 8
    Electronic Resource
    Electronic Resource
    Stability of Linear Inequality Systems Measured by the Hausdorff Metric (2000)
    Springer
    Set-valued analysis 8 (2000), S. 253-266 
    Details
    ISSN: 1572-932X
    Keywords: Hausdorff metric ; linear inequality systems ; stability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Notes: Abstract In this paper, we propose a Hausdorff metric to measure the “distance” between two linear inequality systems on a real normed space X. For this topology, which comes through a pseudo-metric in the set Σ of linear inequality systems, the closedness of the feasible set mapping is studied, and at the same time a characterization of the stability of the subset Σ c of consistent sytems is given.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1008701026782
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  • 9
    Electronic Resource
    Electronic Resource
    Preparation of colloidal Fe3O4 ultrafine particles in microemulsions (1994)
    Springer
    Journal of materials science 29 (1994), S. 3797-3801 
    Details
    ISSN: 1573-4803
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The preparation of magnetite particles is reported from the precipitation of Fe2+/Fe3+ with NH4OH in several kinds of microemulsions: AOT/n-heptane/water microemulsions and a new non-toxic microemulsion system whose phase behaviour and structure has been recently studied. It is shown that both the droplet size and the presence of interactions in the dispersed phase greatly influence the final size of the obtained particles. In addition, the size of the particles can be increased by successive repetition of the reaction inside the droplets of the microemulsion.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00357351
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  • 10
    Electronic Resource
    Electronic Resource
    Multimicroprocessor system for online monitoring in a CCU (1990)
    Springer
    Medical & biological engineering & computing 28 (1990), S. 339-349 
    Details
    ISSN: 1741-0444
    Keywords: Arrhythmia detection ; CCU patient monitoring ; Multimicroprocessor applications ; Physiological signal processing
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract A real-time monitoring system for physiological signals, developed for patients in coronary care units (CCUs), is described. This system monitors the signals that have the greatest clinical value in a CCU environment (ECG and cardiovascular pressures), taking charge of detecting dangerous situations and of extracting information significant to the correct monitoring of the patient. The information it extracts, mainly from the ECG, is presented to the user in an ergonomic way using written reports and graphs which collect and compile the information, facilitating its interpretation. Some utilities have been developed to allow the user to modify certain monitoring conditions as well as to correct results derived from them, thereby improving the reliability of the monitoring process. The system uses a multimicroprocessor architecture (imposed by the need to perform a large number of tasks in real time) with a block based on the VME bus, charged with acquiring and processing the monitored signals, and an IBM-compatible PC/XT which is used as a system user interface and a massive storage device in which the information resulting from the monitoring of signals is stored.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02446152
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