Library

feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
Filter
  • Articles: DFG German National Licenses  (86)
Source
  • Articles: DFG German National Licenses  (86)
Material
  • 1
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 73 (1993), S. 5309-5314 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Giant negative magnetoresistance (GMR) has been observed in a number of granular ferromagnetic systems [Co–Ag, Co–Cu, Fe–Cu, Fe–Ag, and (Fe–Ni)–Ag] with effect sizes as much as 85% at 5 K and 25% at 300 K. It is shown that the GMR is isotropic and is due to magnetic scattering of the conduction electrons by the nonaligned magnetic entities. The essential contribution to the resistivity is ρm[1−F(M/Ms)], where F(M/Ms) measures the spin disorder from ferromagnetic alignment and ρm is the magnetic resistivity that defines the size of the GMR. The magnitude of GMR is affected by the size and density of the magnetic entities which can be controlled by varying the composition and the process conditions. When the composition is varied, the maximum GMR is realized in systems with magnetic constituents of about 25%.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 2
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 73 (1993), S. 6949-6951 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We have produced granular Ni–Al2O3 solids by magnetron sputtering, and the entire composition range has been studied. The percolation threshold (pc) has been identified to be near 55 percent Ni by volume, in agreement with other granular metal systems. Below pc, the samples display typical single domain magnetic behaviors, including superparamagnetism and enhanced coercivity. However, above percolation the samples display ferromagnetic transitions which differ substantially from the transition in pure Ni. We have performed a scaling analysis of the ferromagnetic transition in several such materials, and have obtained values of the Curie temperatures and the critical exponents. These are the first such analyses of the ferromagnetic-paramagnetic transition in granular magnetic solids. We have observed a depression of the Curie temperature as the Al2O3 content of the samples is increased, as well as a substantial variation of the critical exponents. The variation of Tc may be understood in terms of finite size scaling.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 3
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 69 (1991), S. 5301-5303 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: It has been found recently that the magnetic surface anisotropy Ks in Fe70B30/Ag multilayer films decreases monotonically with magnetic layer thickness (2L) for 2L〈16.5 A(ring). In order to determine possible effects of the spacer material on the surface anisotropy in the aforementioned system, Ag has been replaced with Al2O3 and ferromagnetic resonance (FMR) measurements have been made on these films. These Fe70B30/Al2O3 films were fabricated by magnetron sputtering and were characterized by x-ray-diffraction and vibrating sample magnetometer (VSM) measurements in addition to FMR. In the region where Ks depends upon 2L, the data is insufficient to confirm the thickness dependence of Ks that was observed in Fe70B30/Ag, while in the region where Ks is independent of 2L, the values of Ks deduced for Fe70B30/Ag and Fe70B30/Al2O3 are in good agreement. The latter is particularly interesting in light of the enormous difference in conductivity between Ag and Al2O3.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 4
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 70 (1991), S. 6308-6310 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Under equilibrium conditions, Gd and Cr are immiscible. However, by vapor quenching using sputtering techniques, metastable GdxCr1−x alloys can be prepared over the entire composition range. Since pure Gd and Cr are ferromagnetic and antiferromagnetic, respectively, such metastable alloys reveal the evolution from ferromagnetic ordering to antiferromagnetic ordering. X-ray diffraction shows that the structure for samples with x〈0.20 is body-centered-cubic, the same as that of Cr, whereas for x(approximately-greater-than)0.20 it is hexagonal-close-packed (hcp), as is Gd. Surprisingly, no single phase amorphous state has been found. Pure Gd is ferromagnetic with Tc near room temperature. With the addition of Cr, Tc decreases slowly to about 226 K at x=0.60, and decreases rapidly as the Gd concentration is further reduced. For samples with x〈0.50, magnetization at 5 K cannot be saturated even in an external field of 50 kOe, due to competing ferromagnetic and antiferromagnetic interactions. A magnetic phase diagram has been determined.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 5
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 70 (1991), S. 6415-6417 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Fe(110)/W(110) superlattices with various Fe and W layer thicknesses have been fabricated by magnetron sputtering and studied by x-ray diffraction (XRD) and superconducting quantum interference device (SQUID) magnetometry. Detailed x-ray analysis reveals that, while the superlattice structure is faithfully reproduced throughout the samples, there is noticeable interdiffusion between the Fe and W layers. Consequently, within the intermixed region a diminution of the Fe moments is observed, while the remaining Fe moments have values close to the bulk value.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 6
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 70 (1991), S. 3275-3280 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The mechanical properties of Ag-Al2O3 and Ni-Al2O3 granular metal films, as well as the magnetic behavior of the nickel-based films, is presented. Enhancements in the mechanical properties of these materials, as measured by low load indentation techniques, were observed for a metal volume fraction p of about 0.55. This volume fraction corresponded to the percolation threshold pc as determined from the magnetic measurements. A peak in the compliance as a function of p was observed, similar to elastic anomalies reported for small bilayer period superlattices. A discontinuity in the rate of change of hardness as a function of p was also observed, and believed to result from a change in deformation mechanism at pc.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 7
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 69 (1991), S. 7375-7375 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 8
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 67 (1990), S. 4518-4520 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: By doping a very small amount of 57Fe into La2CuO4, Mössbauer spectroscopy has been applied to study the magnetic property of the parent compound. From the measurement of the magnetic hyperfine field at the Fe nuclei for various temperatures between 4.2 K and TN, the temperature dependence of the sublattice magnetization for La2CuO4 has been discussed. A theoretical calculation shows that, with temperature increasing a 3D-2D dimensional crossover occurs in the magnetic dynamics of an anisotropic antiferromagnetic, which is indeed confirmed by the data. The best fit to the data using this theory yields J=1600 K and r=0.011.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 9
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 70 (1991), S. 5885-5887 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Ultrafine face-centered-cubic Co particles in a conducting Cu matrix have been produced by annealing of sputtered metastable CoxCu1−x alloy films (0.10≤x≤0.80). The average size of the particles, and therefore the magnetic properties of these materials, can be easily controlled by the processing parameters. Single-domain behavior results in coercivities in excess of 600 Oe, while the magnetization is determined by the choice of alloy composition. The evolution of the structural and magnetic properties have been studied as a function of annealing conditions, and are compared to those previously observed with Fe-based materials.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 10
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 69 (1991), S. 5267-5272 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Granular metals consist of nanometer size metal granules embedded in an immiscible medium. They display a rich variety of physical properties as a result of their unique nanostructure and extra degrees of freedom. They are also suitable for the exploration of finite-size effects, enhanced and tailored properties of fundamental interest, and for technological applications. Granular magnetic solids of elemental metals and alloys will be discussed. Single-domain characteristics, superparamagnetic relaxation, enhanced ferromagnetic properties, granular alloys, and spin glasses are some of the topics covered.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...