Electric Hyperfine Interactions of Iron in Dimeric State in Metals (original) (raw)
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Time-dependent hyperfine interaction of 169Tm in iron
Physics Letters B, 1968
The temperature dependence of the perturbed angular correlation of the 198-110 keV y cascade in 169Tm implanted in iron foil is consistent with a time-dependent magnetic interaction with a relaxation time constant T S -2 ps.
Local structure and hyperfine interactions of57Fe in NaFeAs studied by Mössbauer spectroscopy
Journal of Physics: Condensed Matter, 2013
Detailed 57 Fe Mössbauer spectroscopy measurements on superconducting NaFeAs powder samples have been performed in the temperature range 13 K ≤ T < 300 K. The 57 Fe spectra recorded in the paramagnetic range (T > T N ≈ 46 K) were discussed supposing that most of the Fe 2+ ions are located in distorted (FeAs 4) tetrahedral of NaFeAs phase, while additional minor (< 10%) component of the spectra corresponds to impurity or intergrowth NaFe 2 As 2 phase with a nominal composition near "NaFe 2 As 2 ". Our results reveal that the structural transition (T S ≈ 55 K) has a weak effect on the electronic structure of iron ions, while at T ≤ T N the spectra show a continuous distribution of hyperfine fields H Fe. Shape of these spectra was analyzed in term of two models: (i) an incommensurate spin density wave modulation of iron magnetic structure, (ii) a formation of a microdomain structure or phase separation. It was shown that the hyperfine parameters obtained using these two methods have very similar values over the whole temperature range. The analysis of the temperature dependence H Fe (T) with the Bean-Rodbell model leads to ζ = 1.16 ± 0.05, suggesting that the magnetic phase transition is first-order in nature. A sharp evolution of the V ZZ (T) and η(T) parameters of the full Hamiltonian of hyperfine interactions near T ≈ (T N , T S), were interpreted as a manifestation of the anisotropic electron redistribution between the d xz , d yz-and d xy-orbitals of the iron ions.
A Perturbed-Angular-Correlation Study of Hyperfine Interactions at 181Ta in α-Fe2O3
Hyperfine Interactions, 2004
The hyperfine interactions at 181 Ta ions on Fe 3+ sites in -Fe 2 O 3 (hematite) were studied in the temperature range 11Y1100 K by means of the perturbed angular correlation (PAC) technique. The 181 Hf( j ) 181 Ta probe nuclei were introduced chemically into the sample during the preparation. The hyperfine interaction measurements allow to observe the magnetic phase transition and to characterize the supertransferred hyperfine magnetic field B hf and the electric field gradient (EFG) at the impurity sites. The angles between B hf and the principal axes of the EFG were determined. The Morin transition was also observed. The results are compared with those of similar experiments carried out using 111 Cd probe.
Hyperfine field and hyperfine anomalies of copper impurities in iron
Physical Review C, 2011
A new value for the hyperfine magnetic field of copper impurities in iron is obtained by combining resonance frequencies from β-NMR/ON experiments on 59 Cu, 69 Cu and 71 Cu with magnetic moment values from collinear laser spectroscopy measurements on these isotopes. The resulting value, i.e. B hf (CuFe) = −21.794(10) T, is in agreement with the value adopted until now but is an order of magnitude more precise. It is consistent with predictions from ab initio calculations. Comparing the hyperfine field values obtained for the individual isotopes, the hyperfine anomalies in Fe were determined to be 59 ∆ 69 = 0.15(9) % and 71 ∆ 69 = 0.07(11) %.
Evaluation of electric hyperfine interactions inAuFe andCrFe
Hyperfine Interactions, 1994
A detailed analysis of room temperature 57Fe M0ssbauer spectra of A____~e (5 at.% Fe) and CrFe (5, 10 at.% Fe) samples is presented. The deviation from Lorentzian line shape observed in the spectra indicates both thickness effects and structural disorder in these systems. The thickness effect has been taken into account using a new fitting technique that solves the transmission integral numerically rather than relying on the "thin absorber approximation". The present results and analyses using both the thin absorber approximation and the full transmission integral methods on these alloy systems are compared with earlier results obtained on these alloy systems using only the thin absorber approximation.
HYPERFINE INTERACTIONS IN (Gd x Y 1-x ) Fe 2 COMPOUNDS
Le Journal de Physique Colloques, 1976
Rbsum6. -Nous prdsentons les resultats d'une Ctude par effet Mossbauer des composks (Gd,Y I-,)Fez dans un large domaine des temperatures. Les directions des axes de facile aimantation ont 6tC dkterminbes en fonction de la tempkrature et de la composition. Nous discutons le diagramme de rkorientation du spin, en considbrant la competition entre l'anisotropie du sousreseau du fer et celle des interactions d'echange. Nous analysons la dkpendance avec la composition des paramktres hyperfins. La variation thermique des champs internes suggre que la plupart des Clectrons 3d du fer forment une bande ktroite et peuvent &re considbrks comrne localises.
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.
Electronic configuration of Iron (Fe)
2015
Compton profile of Iron was calculated by adopting the Re-normalized-Free-Atom (RFA) and Free Electron models, choosing (3d7-x-4s1+x) configuration, whereas (x=0 to 1step 0.1). This result was compared with recent experimental values. It is seen that the RFA calculation for(3d6.7-4s1.3)configuration gives a better agreement with the experiment. This theoretical Compton profile data have been used to compute the cohesive energy of Iron for the first time and compared it with available data. Also we compute the Band structure and Density of state of Iron crystals(DFTLDA) using code Quantum wise
Physical Review B, 2004
We present a comparison between accurate ab initio calculations and a high-quality experimental data set (1986-2002) of electric-field gradients of Cd at different sites on Ni, Cu, Pd, and Ag surfaces. Experiments found a systematic rule to assign surface sites on (100) and (111) surfaces based on the main component of the electric-field gradient, a rule that does not work for (110) surfaces. Our calculations show that this particular rule is a manifestation of a more general underlying systematic behavior. When looked upon from this point of view, (100), (111) and (110) surfaces behave in precisely the same way. The physical mechanism behind the systematics of the EFG for other 5sp impurities ͑Cd-Ba͒ at different fcc surfaces sites is revealed, showing in a natural way why the first half of the 5p elements shows a coordination dependence that is opposite with respect to the second half.
1976
The density matrix formalism is applied to the interpretation of Mossbauer spectra of single crystals of K3Fe(CN)« taken with polarized y-radiation to find the average electric hyperfine Hamiltonian of the Mossbauer nucleus. Experimental results are given for 57 Fe nuclei in the monoclinic and orthorhombic polytypes. The hyperfine parameters and the orientations of the principal axes vary from one polytype to another. Both polytypes investigated show evidence for more than one inequivalent lattice site, although they are not energetically distinguishable, and an attempt is made in one case to resolve the sites. Some limitations and possible improvements of the accuracy are also discussed.