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The magnetic and structural properties of amorphous (Fe100-xBx)92Sc8 alloys have been investigated in detail. Amorphous (Fe100-xBx)92Sc8 alloys were chosen because boron atoms lead to unexpected modifications in the physical properties, whose measurements, analysis, interpretation and modeling is the aim of the present study. Generally, the introduction of boron atoms in crystalline transition metal alloys such as iron-boron results in a reduction in the magnetic hyperfine field, Bhf, and the magnetic moment at low temperatures. The substitution of iron by boron atoms in amorphous (Fe100-xBx)92Sc8 alloys, however, induces a significant increase in the average magnetic hyperfine fields, while causing a reduction in the measured macroscopic magnetic moments. The latest observation of the proportionality between magnetic moment and Bhf suggests a need for a better understanding of this effect. It will be shown that the spins of 3d-electrons are the key factor for the proportionality between internal magnetic hyperfine fields, Bhf, and magnetic moment. The measured magnetic moment, however, is the sum of the spins of 3d-electrons and magnetic moment of sp-electrons. For this reason, the measured magnetic moment and the behavior of the magnetic moment of 3d-electrons are different. The magnetic moment of 3d-electrons and the sp- moments are, however, the key factors for understanding the magnetic properties of the amorphous (Fe100-xBx)92Sc8 alloys. Another study compared the influence of boron on the 3d magnetic Fe-moment and the macroscopic measured magnetic moment of the sample. Why the measured magnetic moment and the behavior of the moment of 3d-electrons are different is discussed. This report, in addition, emphasizes the influence of atomistic short-range order on the magnetic phenomena.

The relationship between the internal magnetic hyperfine field, Bhf, and the measured magnetic moment of Fe, μFe, has long been a challenge in Mossbauer spectroscopy, nuclear physics and materials science. In many publications, it has been reported that Bhf and μFe are proportional. In contrast, in the present work, it will be shown that the macroscopic measured magnetic moment by methods such as SQUID is the sum of the magnetic moment of delocalized electrons with 3d-character, μ3d, and the moment of electrons with sp-character, μsp. The sp. moment is, however, less significant for the arising of magnetic hyperfine field. Therefore, the direct relation of measured magnetic moment to magnetic hyperfine field of Fe leads to inaccurate interpretations. Instead, it can be shown that Bhf is associated with μ3d. The constant of proportionality, frequently used in Mossbauer spectroscopy, is typically determined from the relationship between measured values of the magnetic moment and the hyperfine fields. Based on the present findings, the constant of proportionality is the results of the relationship between Bhf and the delocalized magnetic moment, μ3d, which is different from the measured magnetic moment. The use of the correct constant of proportionality relating Bhf to the magnetic moment allows the separation of μ3d and μsp. In the present work, this relationship has been studied for crystalline Fe, amorphous Fe90Sc10 and (Fe100-xCoX)90Sc10 alloys, prepared as homogeneous structures or in the form of heterogeneous nanoglass.

A parent compound of iron-based superconductor, Fe1.1Te, and a Se-doped superconductor, FeTe0.5Se0.5, were investigated using 125Te-Mossbauer spectroscopy. By measuring precise temperature dependence of the spectra, discontinuous line broadening in the Fe1.1Te near the antiferromagnetic transition temperature (TN) of Fe was observed. While the broadening of the line width were observed in both samples as the temperature decreases, the temperature dependences of the line width were well reproduced as that of the recoilless fraction, assuming the Debye model with a Debye temperature of about 200 K. The discontinuous additional line broadening in the Fe1.1Te can be considered as the internal magnetic fields of Te below TN, since the temperature dependence of internal magnetic fields of Te is similar to that of Fe in 57Fe-Mossbauer spectroscopy. Therefore, hybridization of the electronic orbital of Te and Fe was suggested and the transferred magnetic moment of Te was induced through the antiferromagnetic order of Fe at TN.

YFexCr(1-x)O3 (0 ≤ x ≤ 1) compounds prepared by autocombustion were studied with X-ray and neutron powder diffraction, Mossbauer spectroscopy and ab-initio electronic structure calculations to try to understand the interplay of magnetic order and structural parameters as a function of doping in this multiferroic material. All samples exhibit the orthorhombic nuclear structure (space group symmetry Pnma) and the cell parameters vary continuously as a function of doping. In the neutron powder diffraction patterns it was observed that in addition to the Pnma nuclear structure peaks reflections are seen in all samples which arise from magnetic order. These peaks can be indexed using the nuclear unit cell indicating an ordering vector of k = (0,0,0). Using representational analysis and Rietveld refinements the magnetic structure was determined to be Pn’ma’ and the mean magnetic moment per transition metal atom was observed to decrease continuously from Fe to Cr. For compounds with x > 0.25 a weak ferromagnetic contribution is also present which is due to a small canting of the moments out of the basal plane. The Mossbauer spectra corroborate the NPD results with all samples showing single magnetic sextets at 4.2 K. The energy gap and the main direct interband transition of the endmember samples were obtained by optical absorption measurements. These optical data were analyzed with the help of DFT band structure calculation using the GGA-PBE + U approximation.

Spin polarized particles exhibiting beta decay, such as, muon and 8Li are very useful for detecting internal magnetic fields in solids. Here, I review our attempts to use these spin polarized beams for battery materials research. Due to a unique lifetime and gyromagnetic ratio of muon, a positive muon spin rotation and relaxation (µ+SR) technique is very popular for studying microscopic internal magnetic fields in condensed matters caused by electron and nuclear magnetism. Particularly in 2009, it was found that Li+ ion diffusion in LixCoO2, which is the most common cathode material in a Li-ion battery, is detectable with µ+SR even under the presence of paramagnetic Co ions (Sugiyama et al., Phys. Rev. Lett. 103, 147601, 2009), while NMR is unable to do so due to the effect of localized magnetic moments on a spin-lattice relaxation rate. Such finding opened the door for µ+SR on energy materials research. Since then, many battery materials have been investigated with µ+SR in order to determine their intrinsic diffusion coefficient (D) of Li+ and Na+ ions. Furthermore, using such intrinsic D, the other important parameters are successfully derived, such as, the reactive surface area, diffusion pathway, and density of mobile ions. In 2018, we have initiated to measure internal magnetic fields in solids with a negative muon, i.e. a µ-SR technique, in J-PARC (Sugiyama et al., Phys. Rev. Lett. 121, 087202, 2018). This will provide a new insight for microscopic internal magnetic fields from lattice sites, while µ+SR does so from interstitial sites. On the contrary, a long lifetime of 8Li (1.21 s) makes a 8Li s-NMR technique suitable for detecting both concentration and diffusion of Li in solids. Particularly in TRIUMF, since the implantation energy of 8Li is tunable from almost 0 to about 28 keV, we can measure both spin-lattice relaxation rate and spin-spin relaxation rate as a function of depth up to about 200 nm, as well as µ+SR using a low energy muon beam in PSI. These will clarify whether the space charge layer of Li+ exists at the interface between electrode and electrolyte material.

Magnesium- and cobalt- substituted FeSb2O4, of composition Fe1−xMgxSb2O4 (x = 0.25, 0.50, 0.75) and Fe0.25Co0.75Sb2O4 have been examined by 57Fe Mossbauer spectroscopy. The complex spectra recorded from the magnetically ordered materials are interpreted in terms of models in which the dominant magnetic interactions occur along the rutile-related chains of FeO6 octahedra in the magnetic structure of FeSb2O4. In materials of the type Fe1−xMgxSb2O4, the diamagnetic Mg2+ ions have no magnetic moment and behave as non-magnetic blocks which disrupt the magnetic interactions in the chains along the c-axis forming segments of iron-containing chains separated by Mg2+ ions. In Fe0.25Co0.75Sb2O4 the spectra are composed of components from different configurations of neighbouring Fe2+ and Co2+ ions.

We present two Penning trap experiments concerned with different aspects of the physics of extreme electromagnetic fields, the ARTEMIS experiment designed for bound-electron magnetic moment measurements in the presence of the extremely strong fields close to the nucleus of highly charged ions, and the HILITE experiment, in which well-defined ion targets are to be subjected to high-intensity laser fields.

We present the study of effect of the particle size on the structural and magnetic properties of the Fe67.5Ni32.5 alloy, prepared by mechanical alloying (MA). After milling the powders during 10 hours they were separated by sieving using different meshes. The refinement of the X-ray patterns showed the coexistence of the BCC (Body Centered Cubic) and the FCC (Face Centered Cubic) phases in all samples with lattice parameters and crystallite sizes independent of the mean particle size. However, big particles presented bigger volumetric fraction of BCC grains. The Mossbauer spectra were fitted with a broad sextet corresponding to the ferromagnetic BCC phase, a hyperfine magnetic field distribution and a broad singlet which correspond to the ferromagnetic and paramagnetic sites of the FCC phase, respectively. Hysteresis loops showed a magnetically, soft behavior for all the samples, however, the saturation magnetization values are smaller for the original powder and for the powders with small, mean, particle size due to the dipolar magnetic interaction and the smaller mean magnetic moment, respectively. These effects were proved by Henkel plots that were made to the samples.

Ab initio calculations of the magnetic and electric hyperfine fields and the magnetic moments were performed for the Fe doped SnO2 dilute magnetic semiconductors with the Wien2k code embodying the full-potential linearized augmented plane-wave method. The calculated results for the neutral system and the different charged state systems with and without the oxygen vacancy show clearly that the ground state is all magnetic and that the addition of electrons and the appearance of oxygen vacancy can increase the magnetic moment and the magnetic hyperfine field and reduce the electric hyperfine field. The energy level splitting of the Fe-3d orbit can lead to enhancing the magnetic moment and, therefore, a very large magnetic moment of 5 μ B is obtained for the Sn15Fe1−O32 charged system.

Synchrotron-Radiation-based $^{\mathrm {149}}$ Sm Mossbauer spectroscopy was applied to Sm intermetallics, SmBe13 and SmTi2Al20. Temperature dependence of the Mossbauer parameters in SmBe13 indicate the Sm valence state is purely trivalent. SmBe13 also showed second-order Doppler shift in synchrotron-radiation-based $^{\mathrm {149}}$ Sm Mossbauer spectroscopy. The Mossbauer parameters obtained in SmTi2Al20 suggest that the Sm valence is fluctuating and the magnitude of the magnetic moment is reduced by hybridization between 4f and conduction electrons and/or effect of crystal electric field.

The magnetic and hyperfine properties of iron impurities in 3C- and 6H- silicon- carbide are calculated using the abinitio method of full-potential linear-augmented-plane- waves. The iron atoms are introduced at substitutional carbon, FeC, and silicon, FeSi ,s ites as well as at the tetrahedral interstitial sites with four nearest neighbours carbon atoms, FeI (C), and four nearest neighbours silicon atoms, FeI (Si). The effect of introducing vacancies at the neighbours of these sites is also studied. Fe atoms with complete neighbors substituted at Si or C sites are found to be nonmagnetic, while Fe atoms at interstitial sites are magnetic. Introduction of a vacancy at a neighboring site reverse the picture.

We have determined the magnetic structure of the intermetallic compound GdGa by 155Gd Mossbauer spectroscopy and neutron powder diffraction. This compound crystallizes in the orthorhombic (Cmcm) CrB-type structure. It orders ferromagnetically at T c = 190(2) K and then undergoes a spin reorientation at T SR = 68(2) K. Between T c and T SR , the magnetic structure is characterized by ferromagnetic order of the Gd moments along the b-axis. On cooling below T SR , the Gd 4c magnetic moments split into two groups (2:2). At 3.6 K, the Gd moment is 6.7(4) μ B , and the Gd magnetic moments are in the bc-plane, canted by 84(3)° and 46(4)° with respect to the crystallographic b-axis. This splitting into two magnetically inequivalent sites is confirmed by our 5 K 155Gd Mossbauer results.

The insulating and antiferromagnetic double perovskite Sr2FeOsO6 has been studied by 57Fe Mossbauer spectroscopy between 5 and 295 K. The iron atoms are essentially in the Fe3 + high spin $( {t_{2\mathrm{g}}{^3} e_\mathrm{g}{^2} } )$ and thus the osmium atoms in the Os $^{5+} ( {t_{2\mathrm{g}}{^3} } )$ state. Two magnetic phase transitions, which according to neutron diffraction studies occur below T N = 140 K and T 2 = 67 K, give rise to magnetic hyperfine patterns, which differ considerably in the hyperfine fields and thus, in the corresponding ordered magnetic moments. The evolution of hyperfine field distributions, average values of the hyperfine fields, and magnetic moments with temperature suggests that the magnetic state formed below T N is strongly frustrated. The frustration is released by a magneto-structural transition which below T 2 leads to a different spin sequence along the c-direction of the tetragonal crystal structure.

Fucan-coated magnetite (Fe3O4) nanoparticles were synthesized by the coprecipitation method and studied by Mossbauer spectroscopy and magnetic measurements. The sizes of the nanoparticles were 8–9 nm. Magnetization measurements and Mossbauer spectroscopy at 300 K revealed superparamagnetic behavior. The magnetic moment of the Fe3O4 is partly screened by the Fucan coating aggregation. When the magnetite nanoparticles are capped with oleic acid or fucan, reduced particle-particle interaction is observed by Mossbauer and TEM studies. The antitumoral activity of the fucan-coated nanoparticles were tested in Sarcoma 180, showing an effective reduction of the tumor size.

We report on the synthesis and characterization of uncoated and gold coated magnetite nanoparticles. Structural characterizations, carried out using X-ray diffraction, confirm the formation of magnetite phase with a mean size of ~7 and ~8 nm for the uncoated and gold covered magnetite nanoparticles, respectively. The value of the gold coated Fe3O4 nanoparticles is consistent with the mean physical size determined from transmission electron microscopy images. Mossbauer spectra at room temperature are consistent with the thermal relaxation of magnetic moments mediated by particle-particle interactions. The 77 K Mossbauer spectra are modeled with four sextets. Those sextets are assigned to the signal of iron ions occupying the tetrahedral and octahedral sites in the core and shell parts of the particle. The room-temperature saturation magnetization value determined for the uncoated Fe3O4 nanoparticles is roughly ~60 emu/g and suggests the occurrence of surface effects such as magnetic disorder or the partial surface oxidation. These surface effects are reduced in the gold-coated Fe3O4 nanoparticles. Zero-field–cooled and field-cooled curves of both samples show irreversibilities which are consistent with a superparamagnetic behavior of interacting nanoparticles.

We report our studies in various fields of Physics through nuclear moments utilizing the β-NMR technique, including material sciences, nuclear structures and fundamental symmetries. Especially, we focus on the recent progress in the studies on the electronic structure in Pt through Knight shifts of various impurities, lattice locations of impurities, electric field gradients, the analysis of nuclear spin in terms of its components, anomaly in the spin expectation value for 9C-9Li mirror pair, the G-parity conservation law, and the Ramsey resonance on UCN for future neutron EDM measurements.

NANOPERM-type alloy with chemical composition Fe76Mo8CuB15 was studied by combination of 57Fe Mossbauer spectroscopy and 57Fe(10B, 11B) nuclear magnetic resonance in order to determine distribution of hyperfine magnetic fields and evolution of relative concentration of Fe-containing crystalline phases within the surface layer and the volume of the nanocrystallized ribbons with annealing temperature. Differential scanning calorimetry revealed two crystallization stages at T x1 ∼ 510 ∘C and T x2 ∼ 640 ∘C, connected to precipitation of α-Fe and Fe(Mo,B) nanocrystals, respectively. The amorphous and partially crystalline state was obtained by annealing at several temperatures in the range 510-650 ∘C. The combination of conversion electron (CEMS) and transmission Mossbauer spectrometry (TMS) showed that annealing induces crystallization starting from both surfaces of the ribbons. For the as-quenched sample, scanning electron microscopy (SEM) and CEMS revealed significant differences in the “air” and “wheel” sides of the ribbons, crystallites were preferentially formed at the latter. While SEM micrographs of annealed samples showed various mean diameters of the crystals at opposite sides of the ribbons, the amounts of crystalline volume derived from the CEMS spectra approximately equaled. Mossbauer spectra of annealed samples contained narrow sextet ascribed to crystalline α-Fe phase, three sextets with distribution of hyperfine field assigned to the interface regions of the nanocrystals and the contribution of the amorphous phases. In-field TMS performed at 4.2 K with magnetic moments aligned by external magnetic field enabled to properly determine in particular the contribution of the amorphous phases in the samples. Resulting distributions of the hyperfine fields were compared with 57Fe(10B, 11B) nuclear magnetic resonance (NMR) spectra.

The magnetic moment and spin fluctuation temperature of isolated Fe impurity atoms in Pd1−xVx (0 ≤ x ≤ 0.15) alloys have been studied by time differential perturbed angular distribution (TDPAD) technique. With increasing V content in Pd matrix, a large non-linear reduction of the local magnetic moment accompanied with an exponential increase of the spin fluctuation temperature TSF has been observed. At and beyond x = 0.12, the Fe atoms are found to be nonmagnetic. As an important new feature, TSF is observed to vary quadratically with composition dependent changes in host spin polarization.

Hyperfine Interaction technique like Mossbauer spectroscopy is a very sensitive tool to study the local probe interactions in Iron doped alloys and compounds. We report here the Mossbauer study of the effect of Fe concentration variations in dilute magnetic semiconducting Se0.004FexSb1−x alloys for x = 0.002, 0.004 and 0.008. The materials were characterized using X-ray diffraction technique (XRD), Fourier Transform Infra-red spectroscopy (FTIR), Neutron depolarization and Mossbauer spectroscopy. The FTIR result shows the semiconducting behavior of the alloys with band gap of 0.18 eV. From Mossbauer spectroscopy two magnetic sites (A and B) were observed. The value of hyperfine magnetic fields (HMF) of ∼ 308 kOe (site A) and 270 kOe (site B) was constant with increase in Fe concentration. A nonmagnetic interaction was also observed with quadrupole splitting (QS) of 1.26 mm/sec (site C) for x = 0.004 and x = 0.008. The Neutron depolarization studies indicate that the clusters of Fe or Fe based compounds having net magnetic moments with a size greater than 100 A is absent.

A new laser installation for the resonance ionization spectroscopy in a laser ion source and for rare isotope production has been put into operation at the IRIS mass-separator, working on-line with the 1 GeV proton beam of the Petersburg Nuclear Physics Institute synchrocyclotron. Isotope shift and hyperfine splitting of 276.9 nm atomic transition in the long chain of Tl isotopes and isomers have been measured. New data on the magnetic moments and changes in mean squared charge radius for 183,184,185,185m,186m2,195m,197mTl have been obtained.

Hyperfine fields of highly-charged heavy ions carrying many electrons are discussed in view of their utility for magnetic-moment measurements on radioactive beams by the recoil in vacuum (RIV) technique. An overview of progress is given along with a review of the foundations for ab initio calculations of the relevant free-ion hyperfine interactions.

The nuclear contribution to the specific heat originates from the combination of a nuclear electric quadrupole interaction and a nuclear magnetic hyperfine interaction of the magnetic atoms embedded in the crystalline lattice structure. We have estimated the nuclear hyperfine level patterns of the nuclear ground state \(I_{g} = 3/2^{-}\) and the first excited state \(I_{ex} = 5/2^{+}\) at 86.5 keV of Mossbauer-active Gd155 nucleus of Gd-based pyrochlores Gd2M2O7 (M = Ti, Sn, Hf, Zr). The nuclear quadrupole and hyperfine interactions are scaled in accordance with the ratios of quadrupole and magnetic moments of \(I_{g} = 3/2^{-}\) state of Gd155 and Gd157 nuclei to get the contribution from Gd157 nucleus of Gd2M2O7 to the hyperfine specific heat Chf appropriate to its relative isotopic abundance. It is found that Chf(T) shows a Schottky hump around 6–8 mK for these pyrochlores. At temperatures much higher than the hyperfine level splitting, Chf behaves as AT − 2 with A ∼ 1–2 × 10 − 4 JK/mole-Gd which is consistent with experimental results.

Precision spectroscopy of hadronic atoms is a powerful tool to study the particle properties (mass and magnetic moment) as well as the hadron-nucleon (nucleus) strong-interaction parameters. Recent developments in hadronic-atom studies, pionic-atom and kaonic-atom spectroscopy in particular, are discussed.

In the present paper, we report a comparison study of SrFe$_2$As$_2$ and SrFeAsF using M\"ossbauer spectroscopy. The temperature dependence of the magnetic hyperfine field is fitted with a modified Bean-Rodbell model. The results give much smaller magnetic moment and magneto-structural coupling effect for SrFeAsF, which may be understood as due to different inter-layer properties of the two compounds., Comment: 4 pages, 2 figures,conference ICAME2011, to be appear in Hyperfine Interactions

The Al46Cu23Fe13 quasicrystal phase, prepared by arc-melting and nanostructured using high energy ball milling technique, was studied employing X-ray diffraction, transmission electron microscopy, ferromagnetic resonance and electric transport measurements. Fe local environments were studied by Mossbauer spectroscopy. The resistivity ratio R(4.2 K)/R(300 K) is within the expected values commonly observed in an icosahedral phase. In general, the experimental results show that an appropriate heat treatment of the as-cast alloy prepared by arc-melting makes possible to obtain good quasicrystal samples. On the other hand, for milling time longer than five hours, the average grain-size of quasicrystal phase reduces, but it preserves Fe local atomic orders. It is also observed that the quasicrystalline sample decomposes in an iron rich nano-quasicrystalline phase and a e-Al2Cu3 phase. Electric transport measurements show that at low temperatures the nano-quasicrystalline samples behave strongly different to their solid counterparts, an effect attributed to a long-range order reduction and an increasing of grain boundary regions. The presence of local magnetic moments in the nanostructured sample is also discussed.

The hyperfine parameters of hyperfine fields, electric field gradients and isomer shifts at the Fe site are investigated based on the first-principles calculations of the electronic structures using LDA (GGA)+U method in the low-temperature orthorhombic antiferromagnetic phase of undoped BaFe2As2. It is fond that the electric field gradient of Fe nucleus is highly related with the electronic structures close to the Fermi level. Though the addition of negative on-site Coulomb interaction to Fe-3d states improves the calculated magnetic moment of Fe atom and the hyperfine parameters of Fe nucleus when U = −0.1 Ry (−0.08 Ry) for GGA+U (LDA+U) method, a negative U correction does not capture the right physics of this system. The calculations prove the strong coupling between the magnetic, structural and electronic properties in antiferromagnetic BaFe2As2 parent.

The degrees of polarization of proton rich nucleus 28P produced in charge exchange reactions 28Si + 9Be → 28P + X, and 28Si + 1H → 28P + X have been observed at 100A MeV. Utilizing thus obtained polarized nuclei, the magnetic moment of 28P was remeasured, and |μ(28P)| = 0.3115 (34) μN was obtained. β-nuclear quadrupole resonance (β-NQR) of 28P implanted in α-Al2O3 have been observed for the first time, in order to measure the electric quadrupole moment of this nucleus.

The Larmor precession for the 362 keV state in 165Ho(Iπ = 3/2 + , T1/2 = 1.512 μs) in Dy2O3 with an external magnetic field of 0.3 T was determined to be − 32.3 ± 0.6 MHz by use of the perturbed angular correlation technique, intending to determine the magnetic moment and apply it to the measurement of the hyperfine field at Ho in Fe. The magnetic moment for this state was tentatively deduced under the assumption that the paramagnetic correction factor for a free Ho3 + ion is applicable to the present case. The independent A22 measurement for the 633 − 362 keV γ cascade for the sign assignment of the Larmor frequency is inconsistent with that from known multipolarities and mixing ratios for this cascade, implying that the mixing ratios may be different from the reported values.

In order to investigate the electronic state, the local structure, and the magnetic structure of a new ion oxide Fe3B7O13(OH), we have applied 57Fe Mossbauer spectroscopy. The room-temperature values of isomer shift and quadrupole splitting are 1.16 mm/s and 3.21 mm/s, respectively, which indicate that the Fe ions are in high spin Fe2 + state. The spectrum at 4.2 K is composed of a well-resolved hyperfine sextet with the hyperfine field of 3.6 T. In a trimer, each Fe2 + magnetic moment is supposed to be directed from Fe2 + to OH − .