ISSN:
1089-7550
Source:
AIP Digital Archive
Topics:
Physics
Notes:
The hyperfine field distributions of equal layer thickness multilayered films (MLS) having nominal Co layer thicknesses of 21, 28, and 54 A(ring) and total thickness of about 3000 A(ring) have been measured by NMR spin-echo experiments. We have determined the actual thicknesses of the Co layers using saturation magnetization measurements and modelling the interface shape. Defining the Co layer thickness as where the magnetization drops to one-half of that of pure Co, we find that these thicknesses are 14±2, 17±3, and 38±4 A(ring), respectively, for the 21-, 28-, and 54-A(ring) MLS. These thicknesses are quite insensitive to whether the interfacial shape of the composition profile is assumed to be trapezoidal, sinusoidal (Hanning function) or Gaussian. Co atoms in the magnetic portion of the film having one or more nearest-neighbor Cr atoms would be expected to have hyperfine fields that were so different and spread out from that of Co atoms with all near-neighbor Co atoms that they could contribute negligible intensity to the spectra. Thus it was anticipated that the hyperfine field spectra would mainly arise from Co atoms having all Co nearest neighbors and therefore the spectra of all the MLS would be similar. Indeed the spectra obtained for all these MLS, as well as for a pure Co film, are very similar. They have two broad peaks of slightly lower values than those of pure powdered Co (224±1 vs 228 MHz for the wall center resonance and 218±1 MHz vs 220 MHz for the wall edge resonance). The slight decrease of the resonance frequency is reasonable in these thin film MLS.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1063/1.340847
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