An improved version of the Hesse-Rubartsch method is described. This method is applied, together with an adapted peak shape, to the evaluation of the hyperfine field distribution in an amorphous Fe79.5Si1.5B19 alloy at room temperature. The detailed structure of this distribution is discussed.

http://iopscience.iop.org/article/10.1088/0022-3735/12/11/018/pdf

Evaluation of hyperfine parameter distributions from overlapped Mossbauer spectra of amorphous alloys

The evaluation of magnetic hyperfine field distributions from 57Fe Mossbauer spectra in systems with both magnetic dipole and electric quadrupole interactions is considered. This problem is treated in higher order perturbation theory, and the case of general magnetic texture and isotropic electric quadrupole texture is treated in full. Simple expressions are given enabling the calculation of all spectrum line positions, intensities and widths. It is shown that in cases where first order perturbation treatments yield low-field artifacts in the magnetic hyperfine distribution, this procedure yields much more reliable results. It is also shown that the calculated magnetic spin texture is much more reliable. The asymmetry effects from the electric quadrupole interaction and from a correlation between this and a dipole magnetic field are considered.

Improving the validity of hyperfine field distributions from magnetic alloys: Part I: Unpolarized source☆

A review is presented of the direct fitting procedures which are used in the analysis of Mossbauer spectra. Direct lineshape fitting with alternative profiles as well as shape-dependent, shape-independent and quasi shape-independent distribution fitting methods all can easily be incorporated in one computer program scheme yielding a large versatility for modification and/or extension of the programs according to specific spectra.

On the methodology of the analysis of Mössbauer spectra

The magnetic properties of amorphous yttrium-iron alloys Y1-xFex have been studied over a wide concentration range 0.32<or=x<or=0.88. Appearance of a moment on the iron in the region x=0.2-0.4 is associated with band metamagnetism, just as for cobalt or nickel alloys. An yttrium-rich alloy (x=0.32) shows exchange-enhanced Pauli paramagnetism in large applied fields. In the other samples, the temperature variation of the susceptibility is not reversible below a temperature TH, but the susceptibility maximum occurs at a lower temperature, TM. These properties are characteristic of a spin glass. Competing exchange interactions of both signs, which stabilise helimagnetic structures in some crystalline R2F17 alloys, lead in the amorphous state to spin-glass behaviour and asperomagnetic order. The dominant positive interactions produce short-range ferromagnetic correlations which persist up to room temperature. However magnetic saturation cannot be achieved for any of the alloys in applied fields of up to 180 kOe, indicating that strong negative interactions are also present.

https://iopscience.iop.org/article/10.1088/0305-4608/11/12/018/pdf

Amorphous yttrium-iron alloys. I. Magnetic properties

The temperature dependence of the AC susceptibility Fe-rich Fe-Zr amorphous alloys having mictomagnetic or spin-glasslike behaviour has been measured in a superposed DC field. The Fe-Zr amorphous alloys containing more than 8.6 at.% Zr clearly show sharp peaks at the Curie temperature TC and the spin cluster freezing temperature Tsf. These two temperatures seem to coincide at a critical concentration for the Fe-7.6 at.% Zr alloy, which is considered to be the percolation limit for the long-range ferromagnetic interactions.

http://iopscience.iop.org/article/10.1088/0305-4608/16/7/018/pdf

Mictomagnetism of Fe-rich Fe-Zr amorphous alloys studied by AC susceptibility in a superposed DC field

Mössbauer study of the amorphous alloy Zr100−xFex

Mössbauer spectroscopy of amorphous metglass Fe80B20

Crystallization of amorphous metals

Strange anisotropy in amorphous metals

Mossbauer measurements of amorphous ZrFe and NiZr(Fe) alloys are presented. It is found that the spectra of both materials are very similar. Fitting a distribution of quadrupole splittings to the experimental data one observes that the distributions are also almost identical for both alloys. This suggests that the Fe environment is the same in both cases. A comparison with spectra of crystalline phases allows a tentative identification of the local units around Fe.

M. Ghafari

Papers

Mössbauer study of the amorphous alloy Zr100−xFex

Mössbauer spectroscopy of amorphous metglass Fe80B20

Crystallization of amorphous metals

Strange anisotropy in amorphous metals

Mössbauer investigations of amorphous metal-metal alloys