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  • 1
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 73 (1993), S. 5987-5987 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Brillouin light scattering (BLS) was used to measure magnon frequency versus in-plane field H and in-plane wave vector for a Fe(38 A(ring))/Cr(13 A(ring))/Fe(38 A(ring)) thin film. Both easy [100] and hard [110] field directions were used. The in-plane wave vector was perpendicular to the field. The data were obtained with a high contrast multipass tandem 3+3 Sandercock Fabry–Perot interferometer, with a free spectral range of 30 GHz. The results were correlated with previous hysteresis measurements.1 In the low field region (H〈200 Oe), the magnon frequency decreases with increasing field in a manner consistent with soft mode behavior. The mode frequency in this low field region is slightly different on the Stokes (S) and anti-Stokes (AS) sides of the BLS spectra. At fields of 150–200 Oe one sees a cusp-like minimum in the magnon frequency field dependence. The S and AS frequencies also converge at this point. This is evidence for the antiparallel alignment of the two magnetizations of the Fe layers and the onset of canting.2 At higher fields (250–350 Oe) one sees a jump in frequency, followed by an apparent approach to saturation, and a further increase above 2 kOe. This behavior is basically the same for both field directions, but the frequencies are downshifted somewhat for the hard [110] direction. The wave-number k dependence is weak in the low field region. Above the jump, the magnon frequency shows a distinct increase with k. The substantial frequency increase with field above 2 kOe may indicate conversion to a surface mode character. This is consistent with the k dependence seen at high fields.
    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 75 (1994), S. 3553-3563 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Brillouin light scattering (BLS) in the backscattering configuration has been used to study the magnetic excitations in epitaxial Fe(38 A(ring))/Cr(13 A(ring))/Fe(38 A(ring)) thin-film sandwiches. Spin-wave frequency was measured versus in-plane wave vector k and static in-plane magnetic field H for both [100] and [110] direction fields and with k perpendicular to H. The range of applied fields was 50–1500 Oe. The wave-number range was 0.45×105–2.3×105 rad/cm. The BLS spectra correlate with magnetization versus field profiles and confirm the antiferromagnetic coupling between the Fe layers. Under low-field conditions and near-antiparallel alignment of the Fe layer magnetization vectors, the spin-wave frequencies from the Stokes and anti-Stokes sides of the BLS spectra are different. These frequencies merge at high field. The low-field splitting feature is very sensitive to small differences in thickness for the magnetic layers and indicates a thickness difference of 9%. Matchups between features of the BLS data and magnetization curves were obtained for the following parameters: magnetic layer saturation induction 4πMs=18.6 kG; cubic anisotropy field HA=550 Oe; in-plane [110] uniaxial anisotropy field HU=76 Oe; antiferromagnetic interlayer exchange coupling field HJ=120 Oe. Spin-wave frequency calculations based on these parameters show quantitative agreement with the measurements. The quantitative fits require inclusion in the theory of an iron layer surface anisotropy with an effective surface anisotropy field of 2 kOe.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Science, Ltd
    Anatomia, histologia, embryologia 28 (1999), S. 0 
    ISSN: 1439-0264
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: The pancreatic β-cell volume was assessed in 12 clinically normal crossbred dogs using immunohistochemical labelling for insulin and computer-assisted morphometric analysis. The β-cell volume was less in the right lobe compared with the body and left lobe, but the β-cell volume did not differ between the body and the left lobe as reported previously. The use of immunohistochemistry, computer-assisted morphometry, the inclusion here of extra-islet β-cells and the exclusion of non-β-endocrine cells in the investigation of the β-cell volume may have contributed to this discrepancy. As most β-cells form irregularly shaped three-dimensional bodies (islets of Langerhans), the effect of the plane of tissue transection (sagittal, transverse, oblique) on the calculation of the β-cell volume was also examined. The β-cell volume in the sagittal plane of the right lobe was lower than the volume in the oblique plane of the same lobe but was not different from the volume in the transverse plane. However, there were no differences in β-cell volume in different planes in the body or left lobe. When quantifying β-cell volume in health or disease, variation in the volume of β-cells in different locations of the pancreas is an important consideration and the plane of transection may also influence results.
    Type of Medium: Electronic Resource
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