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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Journal of molecular medicine 6 (1927), S. 1624-1631 
    ISSN: 1432-1440
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 71 (1992), S. 5199-5204 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We have prepared polycrystalline Co films on epitaxially oxidized Si(111) surfaces and studied their oxidation kinetics under atmospheric conditions using the fact that metallic cobalt is a ferromagnet but CoO is an antiferromagnet and therefore practically nonmagnetic. As a consequence, oxidation is associated with a loss in magnetism. Results show that all samples with an initial thickness of di (approximately-greater-than) 5 nm oxidize practically instantaneously, whereby a constant amount of 2.5 nm of metal is transformed into oxide. For di 〈 5 nm the time constant for oxidation increases considerably and follows an approximately linear dependence with decreasing film thickness, reaching an extrapolated value of τ=190 days for di → 0. This increasing time constant let all samples with di 〈 2.5 nm appear ferromagnetic within the course of this study due to a nonoxidized metallic rest. Auger electron spectroscopy analyses revealed that the main oxidation product is in fact CoO, especially near to the metal interface, but that other compounds are also likely to be formed summing up to a total thickness of 6 nm including adsorbates. A second point of interest was the unidirectional magnetic anisotropy which the oxide imposes to the metal due to an exchange interaction at the interface. This anisotropy shows a sharp onset at a CoO thickness as small as ∼0.25 nm from which an anisotropy constant of ∼4.5×106 J/m3 can be estimated for ultrathin CoO layers.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 77 (1995), S. 6432-6438 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Results are outlined of experimental work concerning Slonczewski's theories explaining 90° coupling: "loose spin'' theory and thickness-fluctuation mechanism. The loose spin theory suggests that 90° coupling originates from paramagnetic impurities in the interlayer of an exchange-coupled layered structure. The influence of these paramagnetic impurities on the magnetic exchange coupling was studied using the wedge technique. High-quality single-crystalline Fe/Ag/Fe samples were prepared in UHV and each sample consisted of two wedges: one wedge with additional Fe deliberately inserted during growth into the Ag interlayer and one wedge with a pure Fe/Ag/Fe structure. The detailed analysis of magneto-optic hysteresis loops revealed quantitatively the bilinearly and the 90° coupling strength. As predicted by loose spin theory additional Fe in the Ag spacer lead to a strong temperature dependence of the 90° coupling. According to the theory an increase of 90° coupling strength proportional to impurity concentration was detected while the strength of bilinear coupling decreased. For the pure Fe/Ag/Fe structure, a linear increase of the 90° coupling strength with decreasing temperature was observed. This result can be explained within the fluctuation mechanism which creates 90° coupling through a combination of interface roughness and intralayer ferromagnetic exchange. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 79 (1996), S. 8578-8583 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: This work investigated the micromagnetic structure of single crystal iron films by means of magnetic force microscopy (MFM) and Kerr microscopy. The investigated samples were epitaxially grown Fe films on a GaAs substrate. The film thickness varied between 30 and 500 nm. With the Kerr microscope it was possible to localize efficiently the domain walls in iron films. These walls were subsequently imaged by MFM with a high resolution. The MFM was used to observe the fine structure of a Bloch wall. Experimental results were compared with the calculated MFM response that was based on a two-dimensional, micromagnetic model describing the magnetic structure of an asymmetric Bloch wall. Both theory and experiment demonstrated the influence of the stray field of the tip on the wall structure. We could observe symmetric Néel walls and cross tie walls in a 30 nm iron film after reducing the sensitivity of the MFM tip. In order to achieve this state the tip was demagnetized by an external field. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 78 (1995), S. 387-391 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We have compared the biquadratic coupling in epitaxially grown Fe/Au/Fe(100)-systems with different interface roughness. The profound short-period oscillations observed on the smooth samples are found to be wiped out for the sample with rougher interfaces. In addition, a stronger biquadratic coupling has been observed. For all measured Au-interlayer thicknesses (1.3–2.4 nm) the biquadratic coupling dominates the antiferromagnetic and ferromagnetic coupling, in contrast to the measurements of the samples with smooth interfaces. The observed increase in biquadratic coupling can be explained in the frame of the currently proposed magnetic-dipole mechanism. The experimental results are in a good agreement with the calculation based on this mechanism, which used the roughness parameters obtained by scanning tunneling microscopy and which did not need any fitting parameters. Thus the existence of the magnetic-dipole coupling mechanism has been confirmed experimentally. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A mechanism resulting in biquadratic interlayer coupling is proposed and analyzed theoretically. This mechanism is connected with the magnetic dipole field, created by magnetic layers with roughness. This field decays exponentially with the distance from the layer, but it shows oscillating behavior in the lateral direction. The scale of both exponential and oscillating dependencies corresponds to the scale of the interface roughness and can reach 20–30 nm. The oscillating variation of the field makes 90° alignment of the magnetization energetically favorable in analogy to the Slonczewski's mechanism. Computer simulations and estimates show that this mechanism can provide a coupling strength of the order of 0.01 erg/cm2 for Fe films with 1 nm interlayer thickness. The part of the work done in Moscow and Jüelich was supported by Collaborative Research Grant CRG 921170 of the NATO Scientific Exchange Programmes. Work at UCSD was supported by the U. S. National Science Foundation. One of us (E.Ts.) is pleased to thank the Alexander von Humboldt Foundation for support.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 63 (1988), S. 3089-3091 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Constant-energy scans in neutron scattering provide a very sensitive tool for testing theoretical line shapes in detail. In order to verify the predictions of asymptotic renormalization-group theory for isotropic ferromagnets above TC we measured the temperature dependence of the paramagnetic scattering from the Heisenberg ferromagnet EuS. The width of the constant-E peaks increases with increasing temperature as predicted. Surprisingly the positions do not scale. The nonuniversal behavior is attributed to the crossover from isotropic to dipolar dynamics.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 61 (1987), S. 3753-3755 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We have studied exchange coupling between ferromagnetic films across nonmagnetic intermediate layers by means of light scattering from spin waves and microwave absorption. The ferromagnetic films were Ni0.8Fe0.2 (permalloy) and Fe and we chose Au, Ag, Cu, V, Cr, Pd, Ge, Si, Mn, and Bi as nonmagnetic interlayer materials. As expected the effective interlayer exchange decreases when the interlayer thickness d0 increases. Minimum thickness d0 where the ferromagnetic films are exchange decoupled range between 10 and 40 A(ring). We compare these results with the concentration dependence of the magnetic ordering temperature in alloys of Fe and Ni with other elements, taking this as a measure for the strength of the exchange. There is a good correspondence which indicates that the coupling effects in the layered structures and the alloys have the same origin which is presumably by RKKY interaction.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 61 (1987), S. 3397-3399 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The paramagnetic scattering from the insulating, isotropic ferromagnet EuS is investigated at TC along the [111] direction by means of inelastic neutron scattering. The energy width of the quasielastic scattering is proportional to qz with z=2.54±0.10, in good agreement with the predictions of dynamical scaling theory (z=2.5). z is, however, significantly larger than the value deduced from measurements along the [100] direction (z∼2.2). Near the zone boundary the magnetic scattering exhibits shoulders the shapes of which deviate from theoretical predictions based on the Heisenberg model.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 61 (1987), S. 3396-3396 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: From single-crystal work we showed previously that, both in absence and at full occupation of the octahedral D atoms, Ce deuteride orders antiferromagnetically (AF).1,2 In the intermediate region the order is ferromagnetic (F). A complete magnetic phase diagram can be found in Ref. 3. Previous authors have measured a lattice distortion in the intermediate concentration region (see references in Ref. 3). However, their data disagree with each other. In order to clarify whether the F order is related to the distortion mentioned above, we have investigated the structural transformations in the region of F to AF around the metal-semiconductor transition at D/Ce≈2.7. Due to the extremely small paramagnetic region around D/Ce≈2.7, reliable results can only be obtained by using the same crystals for the different experiments. The results of x-ray, neutron diffraction, and DTA experiments will be compared with the magnetic phase diagram.
    Type of Medium: Electronic Resource
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