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M ö ssbauer spectroscopic studies by T.SHINJO

M ö ssbauer spectroscopic studies by T.SHINJO. Degree of interlayer mixing is different at the two interfaces (head and tail). A result for Fe layer in contact with Mn layer is shown here. Sample A is prepared by depositing 56 Fe(100 Å) - 57 Fe(3.5Å)-Mn(100Å).

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M ö ssbauer spectroscopic studies by T.SHINJO

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  1. Mössbauer spectroscopic studies by T.SHINJO

  2. Degree of interlayer mixing is different at the two interfaces (head and tail). A result for Fe layer in contact with Mn layer is shown here. Sample A is prepared by depositing 56Fe(100Å)-57Fe(3.5Å)-Mn(100Å). While B is prepared by depositing Mn(100Å)-57Fe(3.5Å)-56Fe(100Å) A shows the situation of Mn-on-Fe, While B shows Fe-on-Mn. Spectrum for A is entirely ferromagnetic but that for B includes a large non-magnetic fraction. The result means that the mixing in Sample A is limited but a considerable mixing happened in Sample B. Such a phenomenon occurs generally if one component is rather reactive. Sample structure Spectra at RT

  3. Spectra of ultrathin Fe layers sandwiched in MgF2 The thinnest layer (Fe16Å) shows a decrease of hyperfine field at RT and an increase at 4K T.Shinjo et al.. Proc.Inter.Vac.Cong. (Vienne,1977)

  4. Mössbauer spectra for Fe/Mg multilayers • measured at 4K. • Sample structure is [Fe(aÅ)/Mg(b Å)]x50. • a is from 1Å to 30Å (as indicated in the figure) • while b is always 20Å ～30Å • Results • Fe monoatomic layer is entirely • ferromagnetic 4K. • Magnetization is oriented perpendicular to the • film in the monolayer region and turned out to be • in-plane for a > 10Å . • Structure of Fe layer is crystalline for a >15Å • but amorphous-like for a < 12Å • K.Kawaguchi et al. J.Phys.Soc.Jpn.55(1986)2375. . • . Crystalline --------------- Amorphous

  5. Mössbauer spectra at 4K of Fe/rare-earth multilayers. Perpendicular magnetization appears for Pr,Nd and Tb. y K.Mibu and T.Shinjo, Hyper.Int. 113(1998)287.

  6. Evidence of Fe5+ Charge disproportionation of Fe in CaFeO3, 2Fe4+ ↔Fe3+ + Fe5+. Temp.dep.of the difference of IS(↑), and hyperfine field(←). At 110K ～285K At RT, a single line is observed, which corresponds to Fe4+. Below 280K, two isomer shifts are observed, due to the charge disproportionation. Magnetic order appears below 110K and 2 different hyperfine fields are observed at 4K. The larger one, 415kOe is close to the typical value for Fe3+. Therefore the other is attributed to Fe5+. The spectrum with applying 48kOe suggests a non-collinear spin structure. At 4K, with and without 48kOe T.Shinjo et al. Ferrites, Proc.Int.Conf.Japan(1980)

  7. Mössbauer spectrum of natural Feat ultralow temperature (5 milli-Kelvin) Intensity of P1 is usually equal to that of P6, At normal temperatures, the levels A and B are equally distributed since the energy separation by the hyperfine field, 34T, is only 2mK. At ultralow temperatures, however, the Boltzmann population deviates from equal (nuclear polarization）.. P1 P6 A B Mössbauer spectrum of a natural iron foil at extremely low temperature. The asymmetry of the 6-line is caused by the nuclear polarization at the ultralow temperature and P6/P1 indicates the relative populations at level B and A, which is determined by Hn/kT. Since the hyperfine field is 34T, the temperature can be estimated to be 5mK. T,Shinjo, Hyper.Int.42(1988)1173.

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