Mössbauer effect studies of Dy[(Fe0.7 Co0.3)1−x Alx]2 intermetallics (original) (raw)
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On the magnetic properties and hyperfine fields in Fe-containing alloys: A theoretical study
physica status solidi (c), 2006
PACS 71.15. Mb, 75.50.Bb In this work, WIEN2k package has been used to calculate the structural and magnetic characteristics, and the hyperfine fields in a series of 1:1 ordered iron binary alloys and intermetallics FeT (T = Ti, V, Cr, Mn, Co, Ni). This is done by solving Kohn-Sham equations using the Full-Potential Linearized Augmented Plane Wave (FP-LAPW) method. In the calculations, the Local Spin Density Approximation (LSDA) and the Generalized Gradient Approximation (GGA) were used for comparison. The results were compared with other theoretical and experimental measurements. Based on our results, GGA is found to be better than the LSDA in evaluating the hyperfine fields. Also the hyperfine fields in the ordered phases were found to be smaller than the hyperfine fields in the disordered phases of the studied systems.
Mössbauer effect studies of Dy(Mn0.4−xAlxFe0.6)2 compounds
Journal of Alloys and Compounds, 2004
It was previously found that the magnetic hyperfine fields observed at 57 Fe nuclei (4.2 K) in the Dy(Mn 1−x Fe x ) 2 and Dy(Fe 1−x Co x ) 2 intermetallics form a Slater-Pauling curve. Both 3d subbands in the Dy(Mn 0.4 Fe 0.6 ) 2 compound are filled up only partially with 3d electrons. The consequence of Mn/Al substitution, in the Dy(Mn 0.4 Fe 0.6 ) 2 compound was studied in the present paper. For this purpose the synthesis and X-ray analysis (300 K) of the series Dy(Mn 0.4−x Al x Fe 0.6 ) 2 were performed. The cubic, MgCu 2 -type Fd3m crystal structure was observed across the series. Nevertheless for x = 0.35 and 0.40 a stoichiometric admixture of the hexagonal, MgZn 2 -type, P6 3 /mmc was evidenced. 57 Fe Mössbauer effect measurements for the series were performed at 4.2 K. The magnetic hyperfine fields form a separate branch of the Slater-Pauling curve. This branch is compared to the magnetic hyperfine field previously obtained for the Dy(Mn 0.4 Fe 0.6−x Al x ) 2 series (the Fe/Al substitution). The possible 3d electron band structure is discussed qualitatively within the Stoner model.
Synthesis, crystal structure and Mössbauer effect studies of Dy(Mn0.4Fe0.6−xAlx)2 intermetallics
Journal of Alloys and Compounds, 2004
It was previously found, that the magnetic hyperfine fields observed at 57 Fe nuclei (4.2 K) in the Dy(Mn 1−x Fe x ) 2 and Dy(Fe 1−x Co x ) 2 intermetallics form a Slater-Pauling curve. Both 3d sub-bands in the Dy(Mn 0.4 Fe 0.6 ) 2 compound are filled up only partially with 3d electrons. The consequence of Fe/Al substitution, in the Dy(Mn 0.4 Fe 0.6 ) 2 compound, was studied in the present paper. For this purpose the synthesis and X-ray analysis (300 K) of the series Dy(Mn 0.4 Fe 0.6−x Al x ) 2 were performed. The cubic, MgCu 2 -type, Fd3m crystal structure was observed across the series. 57 Fe Mössbauer effect measurements for the series were realized at 4.2 K. The obtained crystallographic data and the hyperfine interaction parameters are presented. The magnetic hyperfine fields form a separate branch of the Slater-Pauling curve. The data are qualitatively related to the Stoner model.
Hyperfine interactions in R x Gd1− x Fe3 intermetallics R = Tb, Y
Hyperfine Interactions, 2014
The structural and magnetic properties of rare earth iron intermetallic compounds Tb x Gd 1−x Fe 3 and Y x Gd 1−x Fe 3 (x = 0.0, 0.1, 0.2, 0.4, 0.5, 0.6, 0.8, 1.0) was studied by X-ray diffraction, the 57 Fe Mössbauer effect and SQUID measurements. All investigated compounds crystallize in the rhombohedral PuNi3-type of crystal structure. The investigation of magnetic properties of R x Gd 1−x Fe 3 proved their ferrimagnetic behavior. The Curie temperature of the investigated compounds decreases with the increase of R concentration from 721K (GdFe 3) to 655K (TbFe 3) and 533K (YFe 3). The saturation magnetic moment MS in the R x Gd 1−x Fe 3 system increase with x parameter. The Mössbauer spectra are analyzed using four sextets, corresponding to three crystallographically (b, c, h) and four magnetically (b, c, h 1 , h 2) inequivalent sites for iron. The mean hyperfine magnetic field increases with increase of the Gd concentration
Physical Review B, 2005
Electronic structure spin-polarized calculations with the discrete variational method in density functional theory were performed for 79-atoms embedded clusters modeling the ferromagnetic ͑FM͒ ordered layered compound FeNi ͑tetrataenite͒, as well as disordered Fe-rich fcc Fe-Ni alloys containing ϳ15% Ni in an antiferromagnetic ͑AFM͒ configuration. These phases of Fe-Ni may be obtained by synthetic means, and are also present in meteorites. Spin magnetic moments and spin density maps were obtained from the calculations. The 57 Fe Mössbauer hyperfine parameters isomer shift, quadrupole shift and magnetic hyperfine fields were calculated with the self-consistent charge and spin densities obtained. It was found that for FM ordered FeNi the electric-field gradient is positive; this result, together with the measured positive value of the quadrupole shift, proves that the direction of magnetization is perpendicular to the Fe-Ni layers. For the Fe-rich disordered Fe-Ni alloys with AFM configuration, it was found that the lower values of the isomer shift relative to tetrataenite can only be explained by a lattice contraction.
Magnetic moments and hyperfine fields at Fe in 3d-transition metals
Hyperfine Interactions, 1990
The magnetic moments and hyperfine fields at Fe sites in 3d-transition metals are calculated using the first principle discrete variational method in local density approximation. Although a large positive moment is retained at each Fe site, the hyperfine fields varied from ,large negative to large positive values. It is concluded that the absence of MiSssbauer magnetic splitting does not necessarily imply the absence of local magnetic moments.
Observation of hyperfine structure of D022-Mn3− xFexGa by Mössbauer effect
Japanese Journal of Applied Physics, 2016
In this work, to obtain the design guideline for a magnet made of a Mn-based alloy, Mn3− x Fe x Ga alloys were prepared by arc melting and the magnetic state of Fe in the alloys and hyperfine structure were investigated on the basis of the Mössbauer effect. As a result, D022-Mn2.2Fe0.5Ga alloys were obtained by annealing at 350 °C for 2 days. From the Mössbauer spectrum of Mn2.2Fe0.5Ga, it was clear that Fe replaced Mn in the Mn II site of the D022 structure. In addition, it was also found that the hyperfine field of Fe is extremely lower in the Mn II site than in the Mn I site.