Magnetic hyperfine field for zinc in iron

The magnetic hyperfine field for zinc in iron has been measured by the DPAD method following the reaction ⁶⁴Ni(α, n)⁶⁷Zn^m. Measurements performed with a sandwich target and with ⁶⁴Ni($\text{Fe}$) alloy targets containing 3% and 6% nickel yielded similar results: H_hf(0) = -191 ± 3 kG.     

Magnetic hyperfine field at caesium in iron

We report temperature dependence of nuclear orientation (NO), and the first observation of NMR/ON on Cs in iron.^{132, 136}Cs were implanted at room temperature into polycrystalline and single crystal iron. NO values for the (average) magnetic hyperfine field B_hf (CsFe) are close to 34T, intermediate between the value of 40.7T found in on-line samples made at mK temperatures and the NMR/ON value of 27.8 (2)T. The latter studies. The site/field distribution is briefly discussed. ISOLDE Collaboration, CERN     

The hyperfine field of sodium in iron

The hyperfine field of NaFe has been measured using Low Temperature Nuclear Orientation of cold implanted²⁴Na. The combination of both the γ-and β-anisotropies yields information on the implantation fraction of Na in Fe. Furthermore, an, upper limit for the relaxation time of Na in Fe could be deduced.     

The hyperfine field of oxygen in iron

From an on-line nuclear orientation measurement on¹⁵O implanted in iron, the hyperfine field of oxygen in iron was deduced as +12.2(16) T. This experiment, together with two measurements on¹⁷F, which was implanted in the same foil, also yielded information on the relaxation and implantation behaviour of light impurities when implanted at low dose and at low temperature.     

Magnetic hyperfine field of Ta in iron measured by means of the dpac method

The magnetic hyperfine field of Ta in iron was measured by means of DPAC using the 5/2⁺ state in¹⁸¹Ta. At room temperature, this field was found to be |H _hf(RT)|=6.08(7) T, which confirms the result of an earlier DPAC experiment. A hyperfine anomaly^5/2Δ^7/2=−4.6(23)% between the above state and the 7/2⁺ ground state of¹⁸¹Ta is deduced.     

The hyperfine field of krypton in iron

The hyperfine field of krypton nuclei at lattice sites in iron has been determined using nuclear orientation. From the anisotropy of the electrons emitted in the decay of⁸⁵Kr implanted in iron, a hyperfine field value of +31.2(8) T was deduced for a substitutional fraction of approximately 37%. Also, a relaxation time of the order of 900 see was observed at temperatures between 7 and 11 mK.     

The hyperfine field on carbon in iron

Integral perturbed angular correlation experiments have been carried out on recoilimplanted¹⁵C nuclei in iron. The 739 keV5/2⁺ level of¹⁵C was populated via the¹⁴C(d, p)¹⁵C^* reaction. Using the known g-factor and lifetime of the state, effective internal fields of –12.4±1.1 kG and –10.9±1.5 kG were determined at room temperature and 77 K, respectively. A conduction electron polarization hyperfine field of about –20 kG was deduced from the data.Work supported in part by the National Science Foundation.     

Lattice location,hyperfine field,and radiation damage in Yb-implanted iron

The annealing properties of Yb-implanted Fe were studied up to 600°C by the channeling technique and compared to hyperfine field measurements. Sharp changes in the Yb aligned scattering yields are found after annealing above 400°C, i.e. in the temperature range where the hyperfine field at the impurity falls to zero. Radiation damage evolution, particularly in the {100} planes, is shown to explain the results.     

Magnetic hyperfine field for zinc in nickel

Electron mobility in the narrow band solid with a cellular disorder is investigated by methods of the coherent potential theory. Numerical results for the tight-binding model with the Lorentzian distribution of site potentials are presented. The motion of the electron in the region of extended states is neither a well defined coherent band motion nor a simple Brownian diffusion. The statistical electron-hole correlation proves to be important and increases fast with the potential distribution width to band width ratio. The correlation also increases when approaching the mobility edges.     

Magnetic hyperfine field for arsenic in nickel

The magnetic hyperfine field for As in nickel has been remeasured by DPAD techniques. Using a sandwich type of target the excited As nuclei were recoil-implanted into unpolarized nickel layers after the reaction⁷¹Ga (α, n)⁷⁴As. The resultH _hf (300 K)=106 (2) kOe differs considerably from a former IPAC measurement.     

The hyperfine field of99Tc in iron

The magnetic hyperfine field at⁹⁹Tc impurities in Fe has been measured to be ¦H _hf¦=325 (7) kGauss at 298 °K. The technique of time-differential perturbed angular correlations on the 181 keV state of⁹⁹Tc was used.     

Magnetic field focusing of hyperfine interaction in hydrogen

We find a new correction to hyperfine splitting in the ground state of hydrogen atom in magnetic field. The physical basis for this effect is the reduction of the size of the electron orbit in magnetic field. As a result, the value of the wavefunction at the origin increases which can be called magnetic focusing. Another magnetic-field-induced effect is the appearance of field dependent tensor forces.     

Magnetic hyperfine interaction after77Br implantation into iron

Radioactive⁷⁷Br ions were implanted at 60 keV and 270 keV into polycrystalline iron foils. The magnetic hyperfine interaction of the daughter nucleus⁷⁷Se in the 250 keV isomeric level was investigated using the perturbed angular correlation technique and fast BaF₂ detectors. The Larmor frequency at room temperature was determined as ω_L=1272(2) MHz, leading to a substitutional hyperfine field ofB _hf(SeFe)=62(6) T. The substitutional fraction rises from 21% at room temperature to about 100% at 790 K annealing temperature. No other well-defined magnetic or electric hyperfine component attributable to impurity-defect complexes was identified. The diffusion of Br atoms in the surface region during the annealing process was studied via Rutherford backscattering with 1.0 MeV α-particles.     

Local magnetic moment and hyperfine field in hydrogenated iron and iron-vanadium alloy

The local magnetic moment and hyperfine fieldB _hf at Fe and V sites in hydrogenated iron and iron-vanadium were calculated using the discrete variational method. The variations in andB _hf with H occupation of the octahedral (O) site were considered. It was found that when H occupies the O site neighbouring an Fe atom, both local moment and hyperfine field at this atom decrease linearly with increasing number of H atoms. The rate of decrease is larger for Fe in iron as compared to iron in vanadium. On the other hand, when H resides at an O site next neighbouring an Fe atom, whether in iron metal or in iron-vanadium, the Fe magnetic moment increases slowly, while the hyperfine field remains almost constant. The V moment in iron, which is negative (–0.83 _B ), becomes less negative (–0.30 _B) as H occupies the neighboring O sites, whereas slight changes occur (–0.88 _B) when H is at the next neighbouring O site. The net effect of H on Fe in iron is to decrease the average magnetic moment at a rate of 1.2 _B per H/Fe for low H content. On the other hand, the average Fe moment in an iron-vanadium alloy increases if H resides at O sites which are immediate neigbours of V and next neighbours of Fe. This may explain the development of a magnetic state on hydrogenation of Fe-V alloys, which is exhibited by the specific heat and susceptibility measurements. The changes in the isomer shift were found to agree with experimental trends.     

Magnetic hyperfine field of129I impurities in Pd2MnSb

Conclusions In the Heusler alloy Pd₂MnSb (Z) agreement has been found between the experimental values of magnetic hyperfine fields of 5sp shell impurities Z that substitute Sb and the theoretical predictions of Blandin and Campbell |2|. The decrease of the field when the 5sp shell is nearly full lends support to conduction electron polarization models based on the Daniel Friedel |4| type of theory. In view of these results, the rise of the field of 5sp impurities in iron right up to shell closure remains puzzling.     

Magnetic hyperfine interaction of swift43 K ions recoiling in helium and xenon

The 738 keV 7/2^– isomeric state in⁴³K (=292 ± 5 ns,g=1.266 ± 0.015) was produced in the reaction⁴He(⁴⁰Ar,p) using the 185 MeV pulsed⁴⁰Ar beam of VICKSI and a 2–7 bar helium target cell. The suitability of this isomeric state for hyperfine studies during recoil in gases and after implantation into solids was investigated via the TDPAD technique. The hyperfine deorientation of highly stripped⁴³K ions in He and Xe was investigated and interpreted with the AbragamPound model. When adding up to 15% Xe to the He target gas, a near-exponential loss of alignment with the Xe partial pressure was observed. This effect can be explained by K-hole production in⁴³K in the Xe-K collision for which a cross section of=5 · 10^–18 cm² was estimated.     

Magnetic hyperfine data of non-crystalline iron from Mössbauer spectroscopy

The magnetic hyperfine (hf) data of non-crystalline iron samples, which were prepared in various ways, indicate that the different magnetization behaviour of non-crystalline (nc) and crystalline (crys) material cannot always be related to a random molecular field throughout the nc solid. For heterogeneous samples containing impurity clusters or voids the influence of fluctuations in the local magnetic concentration on the low energy magnetic density of states appears to be predominant.Supported by the Bundesministerium für Forschung und Technologie.