Magnetic hyperfine fields of vacancy-associated119Sn in ion-implanted nickel

Magnetic hyperfine fields of¹¹⁹Sn impurity defects in nickel have been investigated by Mössbauer emission spectroscopy. Radioactive¹¹⁹Xe isotopes were implanted, annealing was performed after¹¹⁹Xe had decayed to¹¹⁹Sb. At least five different components with well-defined magnetic hyperfine fields, isomer shifts and Debye temperatures are identified in the rather complex spectra. One of these (B=2T) is known to be due to substitutional Sn. The hyperfine fields of the other components are pronouncedly larger (B=9T, B=15T, and B=17T, respectively, for single crystals). These defects are proposed to be Sn-multivacancy defects.     

Magnetic hyperfine fields of119Sn in vacancy-associated defect structures in 3d ferromagnets

Hyperfine Interactions - Defect structures associated with Sb or In impurity atoms in iron, cobalt, and nickel hosts have been detected by Sn-119 Mössbauer spectroscopy. With substitutional...     

Anisotropic transferred hyperfine fields acting on 119Sn in gadolinium metal and alloys

Mossbauer studies of 0.1% ¹¹⁹Sn in gadolinium alloys at 4.1 K were performed. The spectra were well reproduced by a superposition of hyperfine fields according to the RKKY model with k_F = 1.27 ± 0.04 A^-1. In Gd_0.95Tm_0.05 where the magnetization is along the c-axis, the transferred field per Gd ion is 4 ± 1% lower than in Gd_0.97Tb_0.03 where the magnetization is perpendicular to the caxis.     

Magnetic properties and 119Sn hyperfine interaction parameters of LiMn6Sn6

We have synthesized LiMn₆Sn₆, the first RMn₆Sn₆ compound involving an alkali metal as R element. It crystallizes in the hexagonal (P6/mmm) HfFe₆Ge₆-type structure. From magnetic measurements and powder neutron diffraction experiments it is found that LiMn₆Sn₆ magnetically orders at T_C = 380 K in a simple easy-plane ferromagnetic structure (m_Mn = 2.58 μ_B at 2 K). The ¹¹⁹Sn M?ssbauer spectrum recorded at 5 K indicates that the tin nuclei experience huge hyperfine fields (as large as 35 T). Electronic structure calculations are used to gain information about the microscopic origin of both the hyperfine field and electric field gradient at the Sn nuclei. The former arises due to spin-dependent hybridization between the 5s states of Sn and the 3d states of Mn. The latter comes from the 5p charge density close to the nucleus, whose anisotropy is mainly produced through directional interactions with the 3d states of the first Mn neighbors. Comparison between experimental quadrupole splittings and theoretical electric field gradients allows us to propose a value of for the quadrupole moment of the first excited state (I= 3/2) of the ¹¹⁹Sn nucleus.     

Influence of chromium on119Sn site hyperfine fields in Fe−Cr alloys

By diffusing¹¹⁹Sn probe atoms into a range of Fe–Cr alloys and carrying out Mössbauer effect measurements it has been shown that Sn site hyperfine fields exhibit the same dependence on chromium concentration as Fe site fields do. It has also been shown that the change in the Sn site field produced by Cr atoms situated in the first or in the second coordination sphere is the same as the corresponding change in the Fe site field. This shows that all the change in the hyperfine field caused by substitution of chromium into an iron matrix is due to conduction electron polarization contributions.     

Magnetic hyperfine fields acting on diamagnetic119Sn impurity in rare-earth-3d transition metal laves phases,crystallized under high pressure

A summary of the magnetic and the electronic properties of Laves Phases compounds RT₂ (R=Sm-Lu; T=Fe, Co, Ni) synthesized under high pressure is presented. The hyperfine fields acting on tin impurity nuclei in RT₂ have been obtained by Mössbauer spectroscopy. It has been found that hyperfine fields at¹¹⁹Sn and their temperature dependences for the RFe₂ (R=Sm-Ho), the RCo₂ (R=Sm-Tb) and GdNi₂ prepared at high and atmospheric pressures, are substantially different, respectively.     

Magnetic hyperfine fields in ferrigehlenites

Western Canadian cretaceous coal (WC5) and Appalachian carboniferous coal (AC4) are good coking coals, although their rheological properties predict a different behaviour with this respect. According to Mössbauer Spectroscopy, iron-based mineral matters of these coals are very different: WC5 spectrum exhibits chiefly Fe₃O₄ while AC4 contains mainly ferrous silicate and no ferric ion. However the spectra of the ashes exhibit a similarity: they characterize α-Fe₂O₃ with a distribution of particle sizes extended down to some tens of nanometers. Such a dispersion could favour catalytic processes during the low temperature stages of coking.     

Magnetic hyperfine fields at Fe,Cd and Sn sites in an FeCo alloy

The magnetic hyperfine field at an Fe site in the ferromagnetic alloy Fe_0.475Co_0.525 was measured using the Mössbauer effect. The value obtained at room temperature was 343 kOe. The hyperfine field at a substituted Cd impurity was measured by the method of time differential perturbed angular correlations. A single frequency was observed at room temperature, corresponding to a field of -177 kOe. Using the Mössbauer effect, the Sn site hyperfine field was measured in a sample in which 0.3 atomic percent of ¹¹⁹Sn had been substituted. The room temperature spectrum consisted of the superposition of a single line, together with a six-line hyperfine spectrum, corresponding to a field of 231 kOe. A phenomenological interpretation is proposed for Fe, Cd and Sn fields in the binary alloys of iron.     

Hyperfine fields at implanted119Sn in Fe

Metastable FeSn systems produced by high dose implantation of¹¹⁹Sn into Fe foils are studied by conversion electron Mössbauer spectroscopy. The hyperfine field experienced by Sn implanted in Fe depends on the implantation dose. Clustering and precipitation of Sn take place at doses of 5x10¹⁶/cm² and beyond. Isochronal annealing of the implanted sample at 500 C causes the Sn atoms to move towards the surface, probably due to vacancy assisted migration, resulting in the precipitation of almost the entire implanted Sn on the Fe surface. This precipitate acts as a source for the in-diffusion of Sn into Fe at 600 C.     

Magnetic hyperfine interactions of 119Sn probe atoms in the binary perovskite CaCu3Mn4O12

The manganite CaCu₃Mn₄O₁₂ doped by ¹¹⁹Sn atoms (about 1 at % with respect to Mn atoms) is studied by Mössbauer spectroscopy. The introduction of diamagnetic tin atoms is found not to affect the structure of the manganite. Tetravalent tin atoms are shown to substitute for the isovalent manganese atoms that are located in an octahedral oxygen surrounding. The cluster method of molecular orbitals is used to calculate the contributions of Mn⁴⁺ and Cu²⁺ cations that belong to different structural sublattices to the hyperfine magnetic field at ¹¹⁹Sn nuclei (H _Sn = 105 kOe at T = 77 K). These partial contributions are analyzed, and the intrasublattice Mn⁴⁺-O-Mn⁴⁺ exchange interactions are found to play a significant role in the formation of the magnetic structure of the manganite.     

Magnetic properties and hyperfine fields of some Eu-compounds with Si,Ge and Sn

Mössbauer effect and magnetization measurements are reported for the intermetallic compounds Eu-(Si, Ge, Sn) and Eu-(Si₂, Ge₂). The equiatomic compounds show a complex magnetic behaviour while EuSi₂ and EuGe₂ are antiferromagnetic. The hyperfine fields at the Eu and Sn sites in EuSn have the same temperature dependence following aS=7/2 Brillouin function.     

Ratios of gI-factors and hyperfine structure anomalies of115Sn,117Sn and119Sn

The ratios of the g_I-factors of¹¹⁵Sn,¹¹⁷Sn and¹¹⁹Sn have been measured by the NMR method in different solutions which have large chemical shifts. No primary isotopic effect on the magnetic shielding was found within the error of 7·10^?7. Therefore the ratios have been used for the calculation of the hyperfine structure anomalies in the³P₁,³P₂ and¹D₂ atomic states of the given tin isotopes.     

Local magnetic structure and anomalies of magnetic hyperfine interactions of57Fe and119Sn nuclei in lithium aluminium ferrites

The⁵⁷Fe and¹¹⁹Sn Mossbauer spectra of ordered ferrites Li_0.5Fe_2.5−xAl_xO₄∶Sn for 0.8<x<1.0 (the compensation point region) have been studied. The spin glass type magnetic structure with the spin canting angle depending on temperature and aluminium concentration is established. Anomalies in the temperature dependence of the hyperfine magnetic field at tin nuclei have been found near the compensation point of the ferrites     

Concerning hyperfine magnetic fields on Mn and Fe nuclei

Summary Utilizing a modified form of Fermi's hyperfine contact Hamiltonian directly derived from the Dirac equation, calculations of the hyperfine magnetic field are performed by considering the Mn and Fe nuclei. Data obtained correct previous results and improve agreement with experiments.     

Calculating the distribution of transferred hyperfine fields at the Sn site in tetragonal CeScSi-type RMgSn compounds

We present a simple model based on an isotropic transferred hyperfine field to calculate the transferred hyperfine field distribution at the Sn site of the antiferromagnetic CeScSi-type RMgSn compounds. The calculations correctly reproduce the main features observed in NdMgSn, TbMgSn, DyMgSn, HoMgSn, and ErMgSn. The transferred hyperfine field distributions are remarkably sensitive to the complex magnetic structures in the RMgSn compounds, and can be used to discriminate between competing magnetic structure models.     

Nuclear moment of the 23.8 keV state and hyperfine anomaly in119Sn

Using the Mössbauer effect of the 23.8 keV transition in¹¹⁹Sn, the nuclear magnetic dipole moment of the 23.8 keV 3/2⁺ state is measured to be 0.632(3)μ _n . From a comparison with previously published results a hyperfine anomaly of ?8.8(5)% is obtained.     

Magnetic hyperfine anomaly in the Mossbauer isotope 119Sn

Using the Mössbauer effect in ¹¹⁹Sn we have measured the ratios of the nuclear g-factors in a uniform applied field. A hyperfine anomaly ¹Δ² = (5.9±2.0)% is obtained, which is thought to be near the purely contact value. A new value of μ_e=+0.643(9) nm is given.     

Magnetic hyperfine fields at sp-impurities in cobalt and nickel

Hyperfine Interactions - The understanding of magnetic hyperfine fields (B hf) at impurity nuclei in magnetic materials has been a central problem in nuclear solid state physics for the last...