Local evidence for re-entrant magnetic behaviour in amorphous Fe90Zr10 alloys

doi:10.1016/0025-5416(88)90293-5

Materials Science and Engineering

Volume 99, Issues 1–2, March 1988, Pages 65-68

https://doi.org/10.1016/0025-5416(88)90293-5 Get rights and content

Abstract

We report results of ⁵⁷Fe Mössbauer measurements on the magnetically concentrated amorphous Fe₉₀Zr₁₀ alloy which give the first evidence of a microscopic origin for the low temperature magnetization anomaly at T_f = 35 K. This is shown by an anomalous increase in the average magnetic hyperfine field $B_{hf} (T)$ below T_f, similar to that observed in crystalline and amorphous re-entrant spin-glass alloys in the concentration range near the percolation threshold.

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Electrical and magnetic properties of amorphous Fe<inf>22.5</inf>Co<inf>22.5</inf>Ni<inf>22.5</inf>Cr<inf>22.5</inf>Zr<inf>10</inf> alloy
2020, Journal of Magnetism and Magnetic Materials
Citation Excerpt :
As for the most ferromagnetic systems, if the empirical approach of Bethe –Slater approach continues to play a major factor for the determination of TC, it has to be assumed that ratio of radius 3d electron of the a-FeCoNiCrZr to the atomic distance is lower than amorphous Fe90Zr10 alloy [8,2]. Contrary to the soft magnetic properties of a-FeCoNiCrZr alloys, (see discussion), the amorphous Fe100-xZrx alloys are magnetically disordered and show a spin-glass re-entrant behaviour with a magnetically random transversal component [9]. The disordered arrangement of atoms in metallic glasses led to a deviation of the electrical properties compared with their crystalline counterpart alloys.
This report is focused on the investigation of electrical and magnetic properties of distorted bcc system. The inspiration for the selection of amorphous Fe_22.5Co_22.5Ni_22.5Cr_22.5Zr₁₀ alloy with a distorted bcc structure is based on the theoretical band calculation. It is confirmed that the free electron density of state of disordered bcc FeNiCr alloy increases at Fermi surface.
Amorphous Fe_22.5Co_22.5Ni_22.5Cr_22.5Zr₁₀ alloy, hereafter denoted as a-FeCoNiCrZr, shows among all the metallic materials the weakest temperature dependence of the electrical resistivity, ρ₀(T). The weak ρ₀(T) has been interpreted in the context of different physical processes such as tunnelling of free electrons and electron phonon interactions.
Magnetically, a-FeCoNiCrZr consists of independent soft ferromagnetic clusters with average cluster size of about 1840 atoms. The Curie temperature, T_C, was verified using Landau’s theory of second-order phase transitions in low non-zero external fields. The reduced magnetization, M(T)/M(0), as a function of reduced temperature, T/T_C, is explained in the framework of the exchange integral fluctuation theory. The exchange integral fluctuation is dominant only at low external fields. At B_ex = 9 T, the exchange integral fluctuation has no noticeable effect on reduced magnetization. At B_ex = 9 T, the precision of magnetic clusters around the B_ex controls the behaviour of reduced magnetization as function of temperature.
Exchange interactions in (FeT)<inf>90</inf>Zr<inf>10</inf> (T = Mn, Ru) metallic glasses
1997, Solid State Communications
We have investigated the bulk and microscopic properties of Fe_90−xMn_xZr₁₀ and compared it with Ru substitution in Fe₉₀Zr₁₀. The spin freezing temperature is only marginally affected by Mn substitution. The bimodal hyperfine field distribution is quantified. The correlated behaviour of high field susceptibility, magnetic ordering temperatures and the low field fraction in hyperfine field distribution all suggest that the low field fraction represents antiferromagnetically coupled spins.
Law of approach to magnetic saturation in inhomogeneous ferri- and antiferromagnets and in amorphous iron-rich Fe-Zr alloys
1994, Journal of Magnetism and Magnetic Materials
The magnetization curve of a two-phase two-sublattice model is calculated analytically. In one phase a ferromagnetic coupling is assumed which contributes to the total magnetization whereas in the other phase a ferrimagnetic interaction takes place. Within the framework of a molecular field theory the magnetization curve of this ferrimagnetic phase is calculated assuming a certain distribution of the molecular field interactions. The law of approach to magnetic saturation yields for the leading term a H⁻¹-dependence in contrast to fluctuations of the local magnetic anisotropy which in general yield a H^{− $built1 2$}-law. The calculations of the two-phase two-sublattice model agree well with measurements of the high-field magnetization curve of amorphous Fe_1−xZr_x-alloys with 0.076 ≤ x ≤ 0.11 showing that with decreasing Zr-content an increase of the ferrimagnetic phase exists.
Mössbauer effect of Fe-rich FeZr amorphous alloys
1993, Nuclear Inst. and Methods in Physics Research, B
AC susceptibility, X_AC and Mössbauer spectra have been measured for Fe_100−xZr_x amorphous alloys (x = 8−12 at.%). The magnetic phase diagram estimated from AC susceptibility measurements shows the re-entrant spin glass state in all of the present specimens, and the hyperfine field distribution curve P(H_hf) at 4.2 K is very broad. These results suggest the magnetic heterogeneity in the specimens. The anomalous increase of average hyperfine fields 〈H_hf〉 below T_sf(〈H_hf〉) may be attributed to the freezing of transverse components of spins.
Itenerant spin glass states and asperomagnetism of amorphous Fe and iron-rich Fe/Zr alloys
1992, Journal of Magnetism and Magnetic Materials
A realistic tight-binding approach for the self-consistent calculation of the itinerant spin configurations of disordered metallic systems has been developed and is used to study numerically the problem of the magnetic states at T = 0 K of iron-rich amorphous alloys of the type Fe_1−xZr_xH_y, and of fictitious amorphous Fe of different densities. In our approach, the local spin polarization is not restricted to the z-direction, i.e. the polarization magnitude as well as its direction can vary from site to site. The calculations show that the spin configurations depend strongly on the preparation, and that changes of the relative spin orientations can lead to drastic changes of the itinerant atomic moments. Metastable spin configurations with essentially isotropic distribution can be prepared by relaxing the system in gradually vanishing external fields with isotropically distributed randomness and zero spatial average, whereas with a non-vanishing average the so-called asperomagnetic configurations are obtained, i.e. ferromagnetic states with randomly frozen transverse components. For iron-rich Fe_1−xZr_x alloys with x = 0.07, according to our calculation, the isotropic spin glass configuration would have slightly lower energy than the asperomagnetic state, by amounts corresponding to ≈ 0.003 eV per electron, while for the hydrogenated system Fe_1-xZr_xH_y with y ≈ 2x, the asperomagnetic state would be favoured by ≈ 0.004 eV. For two computer models of (fictitious) amorphous Fe with densities of 7.39 and 9.19 g cm⁻³, the spin-glass and the asperomagnetic states have roughly the same energy, although for the low-density sample the magnitudes of the moments are quite different in both states.
Itinerant magnetism and spin glass states of iron rich amorphous alloys
1990, Journal of Magnetism and Magnetic Materials
We generalize our self-consistent treatment of the itinerant magnetism of disordered or amorphous transition metal alloys, given in a series of recent papers, in such a way that now also itinerant spin glasses can be treated; i.e. not only the local magnitude, as before, also the local polarization direction can now differ from site, due to a subtle interplay between the isotropic intra-atomic Coulomb interaction and the anisotropic hopping terms in the Hamiltonian. Using a realistic approach with all relevant orbitals, this theory is then applied to a detailed numerical study of the magnetism of iron-rich amorphous Fe-Zr alloys, including hydrogenated samples, and of fictitious amorphous Fe at various densities. As a result we find that in the non-hydrogenated Fe-Zr alloys and in amorphous Fe the transverse components, although summing up to zero, can locally be almost comparable to the longitudinal polarization per atom.

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^☆: Paper presented at the Sixth International Conference on Rapidly Quenched Metals, Montréal, August 3–7, 1987.

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Materials Science and Engineering

Local evidence for re-entrant magnetic behaviour in amorphous Fe90Zr10 alloys☆

Abstract

Phys. Lett. A

J. Appl. Phys.

Phys. Status Solidi B

Phys. Rev. Lett.

Phys. Rev. B

Phys. Rev. Lett.

J. Phys. F

Nucl. Instrum. Methods B

IEEE Trans. Magn. Mag.

IEEE Trans. Magn. Mag.

Phys. Rev. B

J. Appl. Phys.

J. Magn. Magn. Mater.

J. Phys. F

J. Phys. F

J. Magn. Magn. Mater.

J. Appl. Phys.

Electrical and magnetic properties of amorphous Fe<inf>22.5</inf>Co<inf>22.5</inf>Ni<inf>22.5</inf>Cr<inf>22.5</inf>Zr<inf>10</inf> alloy

Exchange interactions in (FeT)<inf>90</inf>Zr<inf>10</inf> (T = Mn, Ru) metallic glasses

Law of approach to magnetic saturation in inhomogeneous ferri- and antiferromagnets and in amorphous iron-rich Fe-Zr alloys

Mössbauer effect of Fe-rich FeZr amorphous alloys

Itenerant spin glass states and asperomagnetism of amorphous Fe and iron-rich Fe/Zr alloys

Itinerant magnetism and spin glass states of iron rich amorphous alloys

Local evidence for re-entrant magnetic behaviour in amorphous Fe₉₀Zr₁₀ alloys☆