Hyperfine field and magnetic moment of V and Cr in iron

The hyperfine fields of ⁵¹V and ⁵³Cr in diluted alloys V_xFe_1?x and Cr_xFe_1?x have been measured by NMR. No concentration dependence is found for x<2%. Therefore we conclude that the magnetic moments of the impurities are constant in contrast to recent neutron scattering results.     

Hyperfine magnetic field on Pt in Gd

The hyperfine field on Pt nuclei in Pt-Gd alloys has been studied using the integral perturbed angular correlation technique (IPAC). Results are given for applied fields between 0.2 T and 4 T in the temperature range 13 K to 300 K.     

Hyperfine magnetic field on Pd in Pd-Fe alloys

The hyperfine field on Pd nuclei in Pd-Fe alloys has been studied using the integral perturbed angular correlation technique (IPAC). Results are given for samples with iron contents from 3 to 60 at.% Fe and the temperature dependence of the hyperfine field is studied for a sample with 10 at.% Fe.     

Hyperfine field at grain boundary atoms in iron nanostructures

Iron nanocrystallites of ball-milled iron powder, partially crystallized melt quenched amorphous alloys and polycrystalline multilayers were studied. The change in the hyperfine field at iron atoms due to grain boundaries does not exceed the experimental linewidth. This revised version was published online in August 2006 with corrections to the Cover Date.     

Hyperfine field and relaxation effect in Li−Zn−Ti ferrites

⁵⁷Fe Mössbauer effect studies were made on titanium substituted Li?Zn ferrite with composition Li_0.45+0.5tZn_0.1 Ti_t Fe_2.45–1.5tO₄ (t=0.0 to 1.2) at 300K. The Mössbauer spectra for t≤0.4 show two well defined Zeeman sextets corresponding to the Fe³⁺ ions at tetrahedral (A) and octahedral (B) sites. The spectra for t=0.6, 0.8 and 0.9 show relaxation but can still be resolved into 2 sextets. The spectra for t=1.0, 1.2 show strong ferrimagnetic relaxation with the spectra for t=1.2 exhibiting an additional central doublet. The effect of Ti⁴⁺ substitution on the Isomer shift (I.S), Quadrupole splitting (Q.S.) and nuclear magnetic fields of Li?Zn ferrites have been reported in this paper. The I.S. was found to be independent of substitution level t, while the quadrupole splitting was observed to be negligible. The variation of hyperfine field with t has been explained on the basis of superexchange interaction and cation distribution.     

Hyperfine quenching of polarized two-electron ions in an external magnetic field

The hyperfine quenching mechanism of metastable states in polarized heliumlike heavy ions is considered. The lifetime dependence of these states on the ion polarization in an external magnetic field is established. This dependence is presented for the ²³P₀ state of the europium (Z=63) ion and is proposed as a method for the measurement of the ion polarization in experiments for the search of parity violating effects.     

Hyperfine field in Li-Zn-Ti ferrites

The paper reports the⁵⁷Fe Mössbauer effect investigations on the solid solutions of Li_0.5Zn_xTi_xFe_2.5–2xO₄ (x=0 to 0. 6) at 300K. The samples with x0.4 exhibit well defined Zeeman pattern consisting of two sextets corresponding to Fe³⁺ ions at tetrahedral and octahedral sites. The composition with x=0.5 shows a strong ferrimagnetic relaxation whereas the composition with x=0.6 exhibits paramagnetic behaviour. The internal magnetic field at⁵⁷Fe nuclei decreases with increasing x at both the sublattices. This variation is explained in terms of cation distribution and super-exchange interactions. The s-electron density has been observed to be independent of substitution level.     

Interplay of iron and rare-earth magnetic order in rare-earth iron pnictide superconductors under magnetic field

The magnetic properties of iron pnictide superconductors with magnetic rare-earth ions under strong magnetic field are investigated based on the cluster self-consistent field method. Starting from an effective Heisenberg model, we present the evolution of magnetic structures on magnetic field in RFeAsO(R = Ce, Pr, Nd, Sm, Gd, and Tb) and RFe_2As_2(R =Eu) compounds. It is found that spin-flop transition occurs in both rare-earth and iron layers under magnetic field, in good agreement with the experimental results. The interplay between rare-earth and iron spins plays a key role in the magneticfield-driven magnetic phase transition, which suggests that the rare-earth layers can modulate the magnetic behaviors of iron layers. In addition, the factors that affect the critical magnetic field for spin-flop transition are also discussed.     

High magnetic field behavior of iron impurities in chromium

Mössbauer measurements in ⁵⁷Fe in dilute FeCr alloys in external magnetic fields up to 140 kOe are presented. The magnetic hyperfine interactions are compared with results obtained by Herbert, Clark and Wilson and are discussed in terms of a model due to Housley and Dash.     

Hyperfine field of samarium in europium monoxide

The hyperfine magnetic field at samarium in europium monoxide at 4.2 K was measured using the time-differential perturbed angular correlation technique. The resultH _hf=147.9±9.7 T indicates a 4f contribution of 130±20 T which is 60% less than the free ion value for Sm³⁺. It is suggested that there exists crystal plus exchange field interactions causing admixtures of the first excited state of Sm³⁺ with its ground state.     

Hyperfine field distributions in ferromagnetic quasicrystals

Recent magnetisation measurements indicated the presence of ferromagnetism in Al−Cu−Mn−Ge quasicrystals with T_c∼535K. In this paper we report the room temperature Mossbauer and X-ray measurements of a series of ferromagnetic AlCuMnFeGe alloys.     

The transient magnetic field for13C in iron

The time-integral transient-field precession has been measured for the first 5+/2 state in¹³C recoiling in magnetized iron at initial velocities ofv _i/v _o=3.4, 5.9, and 8.8. The results are consistent with recent findings for the extremely short-lived (=0.06 ps) 2 ₁ ⁺ state of¹²C. The transient magnetic field is found to exhibit a maximum of 4 MG at a velocity around 4v _o, supporting an interpretation originating in the polarization of halfempty s-shells of the recoiling carbon ions. Closed polycrystalline iron frames were used as ferromagnetic backings, and their properties as such are discussed.     

Hyperfine interactions of iron implanted into aluminium

Stable⁵⁷Fe implanted into Al at energies of 20 to 70 keV and doses of 10¹⁴ to 2·10¹⁷ ions/cm² was studied with conversion electron Mössbauer spectroscopy at room and liquid nitrogen temperatures. Spectra composed of a single line and a doublet were observed. Similarly as in the splat-quenched FeAl alloys iron monomers and iron associations, mostly dimers, are observed. The isomer shifts of both components differ considerably and do not change with iron concentration. The splitting of the doublet increases with iron concentration, the increase being reproduced by computer simulations of electric field gradients in lattices with a random distribution of charge defects. The observed probability of formation of iron associates is higher than in random systems, especially at high iron doses.     

Hyperfine magnetic fields in substituted Finemet alloys

Transmission Mössbauer spectroscopy was used to determine the hyperfine fields of Finemet-type alloys in form of ribbons, substituted alternatively by Mn, Ni, Co, Al, Zn, V or Ge of various concentration. The comparative analysis of magnetic hyperfine fields was carried out which enabled to understand the role of added elements in as-quenched as well as annealed samples. Moreover, the influence of the substitution on the mean direction of the local hyperfine magnetic field was examined.     

Hyperfine interactions in iron — Yttrium oxide systems

Hyperfine interactions of iron — yttrium oxide systems have been investigated by Mössbauer spectroscopy and magnetic measurements. The mixed oxides having varying ratios were prepared by heating the coprecipitated oxyhydroxides to about 1000°C in air. The room temperature Mössbauer spectra are complex in nature and some of them exhibit as may as 10 well resolved peaks consisting of two sets of magnetically split hyperfine six line patterns, indicating existence of two different environments around Fe. The values of specific magnetic susceptibility change with increasing amount of yttrium is maximum for 1:1 (Y:Fe) and then falls continuously. The observed H_n values are less than the reported values for α-Fe₂O₃. From the observed data it appears that a transition for the composition of 1:1 definitely takes place and probably two species are formed. Some of the mixed oxides behave like iron filings in a magnetic field.     

Effect of magnetic field on tempering processes in silicon iron

The effect of magnetic fied on the annealing of silicon iron (3% Si) was studied in the temperature range 480–680°C. The imposition of a magnetic field at 480°C leads to more complete tempering by comparison with similar annealing without field. The effect of the magnetic field on the primary recrystallization texture of the silicon iron is shown: this is expressed in the enhanced scattering of deformation type orientations in the annealing texture.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 1, pp. 82–87, January, 1973.     

Hyperfine field and effect of magnetic dipolar field of Fe−Si single crystal by Mössbauer spectroscopy

A Fe−Si (6at%) single crystal with a (110) surface was studied by a Mossbauer spectroscopy as a function of the angle between a crystal axis <100> and the magnetization direction <hk1>. The difference spectra reveal Si atoms give rise to a magnetic dipolar field, of which magnitude varies with the angle as expected for the Si atom in the 2nd neighbor site. The dipolar field was found to take place at the main lines of Mossbauer spectrum to reveal the Si atom in the 2nd neighbor site never reduces the hyperfine field at the Fe probe nuclei, which supports the earlier proposals by Cranshaw.