Jaroslav Kohout

Charles University in Prague | CUNI

The nanoparticles of ε-Fe2O3 enriched with 57Fe isotope in amorphous silica matrix were prepared by sol-gel technique starting from a single molecular precursor for both Fe2O3 and silica. From the X-ray powder diffraction pattern ε-Fe2O3 was identified as the major phase and α-Fe2O3 and β-Fe2O3 were observed as minor iron oxide phases. Using the lo...

The influence of added sucrose on the phase composition of iron oxide nanoparticles was studied in the Fe2O3/SiO2 nanocomposites. The nanocomposites were prepared by impregnation of mesoporous silica SBA-15 with iron nitrate containing various amounts of sucrose and their subsequent annealing at 1100 and 1200 °C. The phase composition of the iron o...

The nanocrystallization kinetics of Fe${}_{90}$Zr${}_{7}$B${}_{3}$ is investigated by in situ nuclear forward scattering of synchrotron radiation upon isothermal annealing. The nucleation and growth processes are accessed separately for the nanograins, their interfaces, and the residual amorphous matrix by monitoring the time evolution of the corre...

NMR on 57Fe nuclei was measured in two single crystals of magnetite between 4.2 and 135 K (temperature of the Verwey transition TV=121.5 and 123.9 K). We were able to register all lines detected at 4.2 K also at higher temperatures up to TV. The spectra are compatible with the space group Cc, which predicts 8 and 16 lines for iron on tetrahedral (A...

The NMR spectrum of 57Fe nuclei in high purity Y3Fe5O12 garnet (YIG) is reported. The satellite structure of this spectrum is caused by an antisite defect ( Y3+ ion replacing an Fe3+ ion). Resolved satellite lines, which correspond to the Fe3+ ion in six different cation coordination spheres around the defect, are observed. In particular, satellite...

We have prepared silica matrix with hexagonal symmetry of pores (SBA-15) and loaded it with anticancer drug 5-Fluorouracil (5-FU) to promote it as a drug delivery system. Gd2O3 nanoparticles were incorporated into the matrix to enhance nanosystems applicability as contrast agent for MRI, thus enabled this nanocomposite to be used as multifunctional...

In this work, we investigate alternative materials systems that, based on their intrinsic magnetic properties, have the potential to deliver enhanced heating power in magnetic fluid hyperthermia. The focus lies on systems with high magnetization phases, namely iron-nitrogen (Fe-N), iron-boron (Fe-B) and iron-carbon (Fe-C) compounds, and their perfo...

The ⁵⁷Fe-enriched polycrystalline perovskite samples Pb1-xBax(Fe0.5Nb0.5)O3, x = 0.25, 0.5, 0.75 were prepared by a solid-state synthesis and studied in detail by X-ray powder diffraction (XRD), neutron diffraction, measurement of magnetic properties, Mössbauer spectroscopy (MoS), and nuclear magnetic resonance (NMR) in a wide temperature range. Th...

The BaFe12-xTixO19 hexaferrites up to x = 3.00 were extended. XRD patterns were Rietveld fitted for P63/mmc (no. 194) space group and the unit cell parameters were defined. The a parameter and V volume of unit cell change non-monotonically with × while the c parameter has linear behavior. The Ti⁴⁺ cations substitute the Fe³⁺ cations in the 2a, 4fVI...

We present water-insoluble hyaluronan films crosslinked by trivalent iron developed as potential resorbable implants. The films were crosslinked by sorption of ferric salt into solid HA films in water/2-propanol bath. These heterogeneously crosslinked films (het-FeHA) remained tough and dimensionally stable when rehydrated in saline. In contrast, f...

Magnetic behaviour of nanoparticles deviates from their bulk equivalents not only due to finite-size and surface effects but it may be also affected by occurrence of metastable states, such as non-equilibrium cation distribution. The chemical composition along with the specific cation distribution are decisive for magnetic properties of spinel ferr...

BaFe12-xTixO19 barium hexaferrites up to x = 2.00 were synthesized by the usual ceramic technology. Crystal structure refinement was realized by Rietveld method of powder XRD at room temperature. The unit cell parameters change non-monotonically with titanium concentration. The minimum volume of ∼ 698.75 ų was determined for the x = 1.00. The mech...

Spin-driven ferroelectricity phenomena have drawn great interest in the scientific community due to potential application in spintronics and their complex physical mechanisms. A noticeable example of this is multiferroic BaYFeO4 that exhibits an unconventional magnetoelectric (ME) coupling due to the uncorrelated behavior of the ferroelectric and c...

Magnetic nanoparticles of ε-Fe1.76Ga0.24O3 were prepared by thermal treatment of a mesoporous silica matrix impregnated with nitrates. The chosen Ga-doping enhanced magnetization and suppressed the low-temperature spin-reorientation transition typical for ε-Fe2O3. Despite the small mean size of 11 nm, the nanoparticles were in the blocked state ove...

A wise selection of tracers is critical for magnetic particle imaging (MPI). Most of the current tracers are based on superparamagnetic iron oxide nanoparticles (SPIONs) with a suitable coating. We prepared maghemite cores (γ-Fe2O3) by coprecipitation of Fe(II) and Fe(III) salts with ammonium hydroxide followed by oxidation with hydrogen peroxide a...

Iron sulphide Fe3S4, known as the mineral greigite, has been prepared in two distinct nanocrystalline forms with the mean crystallite size of dXRD ≈ 30 and 80 nm via hydrothermal synthesis by using two different surfactants (oleic acid and cetyltrimethylammonium bromide). Their crystallinity and phase purity are probed by X-ray diffraction and Möss...

Hyperfine interactions in Fe78B15Sn7 metallic glass with Co/Fe substitution were investigated by Mössbauer spectrometry. As-quenched samples were prepared by planar flow casting and subsequently annealed at 673 K for 30 min which is in the region of phase transformations determined by differential scanning calorimetry. Magnetic thermogravimetry unv...

Magnetic nanoparticles of ε‐Fe1.76Ga0.24O3 with the volume‐weighted mean size of 17 nm were prepared by thermal treatment of a mesoporous silica template impregnated with metal nitrates and were coated with silica shell of four different thicknesses in the range 6–24 nm. The bare particles exhibited higher magnetization than the undoped compound, 2...

Most magnetic materials studied as negative contrast agents for magnetic resonance imaging (MRI) enter the superparamagnetic state with decreasing size of their particles, which is distinguished by thermal fluctuations of particle magnetic moment. In the present study, a novel type of contrast agents based on non-superparamagnetic nanoparticles (na...

Low temperature magnetic ordering in the LiFePO 4 compound is investigated experimentally using Mössbauer spectroscopy and theoretically via first principles calculations. The evaluation of experiment carried out on a powder sample is compatible with an antiferromagnetic order of Fe ion magnetic moments. When an external magnetic field is applied,...

Controlled thermal decomposition of zinc and iron acetylacetonates in the presence of oleic acid and oleylamine provided surfactant-capped magnetic nanoparticles with narrow size distribution and the mean diameter of ≈15 nm. The combined study by XRD, XRF and Mössbauer spectroscopy revealed three important features of the as-prepared nanoparticles....

Examination of surface microstructure of stainless steels is presented. Transmission Mössbauer spectrometry and Conversion Electron Mössbauer Spectrometry which provide information from the bulk and surface regions, respectively, were used. We concentrate on structural modifications that were caused by surface treatments including grinding, polishi...

The structural and magnetic ordering of Pb2FeSbO6 was studied by means of Mössbauer spectroscopy and neutron powder diffraction in the temperature range from 5 to 300 K. The structural phase transition from the initial cubic phase Fm3¯m to the tetragonal I4/m phase was observed in temperature range 170–190 K. The antiferromagnetic order with a prop...

Magnetic nanoparticles of iron oxides have received extensive attention in the biomedical research, e.g. as prospective contrast agents for T2-weighted magnetic resonance imaging (MRI). The ability of a contrast agent to enhance the relaxation rate of ¹H nuclei in its vicinity is quantitatively described by its relaxivity. Among the polymorphs of t...

Hydrothermal synthesis was employed to prepare three samples of Mn-Zn ferrite nanoparticles with the mean size of crystallites of 12–14 nm, whose compositions were accurately determined by X-ray fluorescence spectroscopy to Mn0.82Zn0.21Fe1.97O, Mn0.70Zn0.31Fe1.99O4, and Mn0.62Zn0.41Fe1.97O4. The X-ray diffraction and SQUID magnetometry were used to...

The ⁵⁷Fe enriched almost single-phase perovskites Pb(Fe0.5Nb0.5)O3 (PFN) and Ba(Fe0.5Nb0.5)O3 (BFN), prepared by a ceramic method (solid-state synthesis), were studied by Mössbauer spectroscopy, nuclear magnetic resonance (NMR), conventional and synchrotron X-ray powder diffraction (XRD). The temperature dependences of hyperfine and structural para...

A spin-reorientation transition from a weakly ferromagnetic (WF) to an antiferromagnetic (AF) spin ordering in hematite (α-Fe2O3) during cooling occurs at Morin temperature (TM∼264 K for bulk). The transition is strongly size dependent and TM generally decreases with the decreasing volume of the particles. For particles smaller than approximately ∼...

The effects of annealing temperature (1000–1125 °C) and Fe2O3 mass fraction (0.3–0.5) in the initial mixture on the composition of ferric oxide polymorphs within the Fe2O3/SiO2 nanocomposite prepared by sol-gel method were investigated. The structural and magnetic properties of prepared samples were characterized in detail by combination of X-ray p...

The catalytic activity of a series of FeOx/Al2O3 prepared under various conditions was evaluated for high temperature decomposition of N2O (HT-deN2O) in the complex gas mixture produced by oxidation of ammonia. Thus the relevant step in the industrial nitric acid production process was simulated. The catalyst stability during a long exposure (12 da...

The long-term stabilities of a group of iron zeolites with MFI, *BEA, and FER structures and similar Fe/Al ratios were evaluated to assess their performance as catalysts for N2O decomposition. Conditions relevant for the application of the catalyst at the secondary level for N2O elimination, i.e., directly after the NH3 oxidation step of the proces...

Mn-Zn ferrite nanoparticles of the composition Mn0.61Zn0.42Fe1.97O4 and mean size of crystallites dXRD = 11 nm are synthesized under hydrothermal conditions as a single-phase product. Subsequently, two coated samples are prepared by encapsulation of the ferrite particles into silica and titania. Transmission electron microscopy confirms the core-sh...

Magnetic nanoparticles have found broad applications in medicine, especially for cell targeting and transport, and as contrast agents in MRI. Our samples of e-Fe2O3 nanoparticles were prepared by annealing in silica matrix, which was leached off and the bare particles were then coated with amorphous silica layers of various thicknesses. The distrib...

We studied the effect of interfaces character in 57Fe/Au thin layers on iron hyperfine parameters using Mossbauer spectroscopy. Four samples of bilayers (57Fe covered by Au) were prepared on MgO substrate by pulsed laser deposition (PLD) with varying 57Fe layer thickness (∼10–95 nm), covered by Au layer with constant thickness of ∼8.7 nm. Mossbauer...

NANOPERM-type alloy with chemical composition Fe76Mo8CuB15 was studied by combination of 57Fe Mössbauer 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...

Iron-based nanoparticles prepared by precipitation from solid solution of saturated binary Cu-Fe alloy were studied by transmission electron microscopy, high-energy X-ray diffraction and Mössbauer spectroscopy. The results showed that the investigated as-prepared nanoparticles contained two phases. The major phase was determined as α−Fe and the min...

The ceramic multiferroic barium iron niobate BaFe0.5Nb0.5O3(BFN) studied in this work belongs to the single-phase perovskites exhibiting high value of dielectric permittivity [1]. The aim of our study was to clarify the transition temperature to magnetically ordered state from the temperature dependence of the hyperfine parameters and magnetic meas...

Sputter-deposited copper ferrite (CuFe2O4) films can be stabilized in cubic or tetragonal structures depending on the deposition conditions and post-deposition heat treatment [1]. The difference is explained by redistribution of cations over particular crystal sites and a distortion of the spinel lattice due to the Jahn-Teller effect of Cu2+ ions....

We present results of the study of structural features of a novel (introduced in 2013) highly corrosion resistant LC 200 N steel, possessing large and stable hardness up to relatively high temperatures and excellent wear resistance. LC200N is a perspective material which can be considered for possible applications in nuclear installations. We have...

Iron is an essential element for most life on Earth, including human beings. Iron is needed for a number of highly complex processes that continuously take place on a molecular level and that are indispensable to human life, e.g. the transportation of oxygen around your body. Iron is required for the production of red blood cells (a process known a...

Low temperature (4.2 K) magnetic behavior of Fe76 Mo 8Cu1B15 metallic glass was studied by 57Fe Mössbauer spectrometry (MS) and 57Fe NMR. Distributions of hyperfine magnetic fields P(B) were determined for as-quenched and annealed (nanocrystalline) samples with relative fraction of the grains about 43%. P(B) distributions were derived for both the...

Mössbauer investigations of iron minerals formed during the process of synthesized ferrihydrite (SF) reduction by anaerobic alkaliphilic bacterium Geoalkalibacter ferrihydriticus and anaerobic thermophilic bacterium Thermincola ferriacetica were carried out involving magnetization measurements. The influence of T. ferriacetica and G. ferrihydriticu...

This contribution aims in characterization of structural positions of iron in human and horse spleen. 57Fe Mössbauer spectroscopy was employed as a principal method of investigation in addition to X-ray diffraction and transmission electron microscopy (TEM). At room temperature, ferritin nanoparticles exhibit superparamagnetic behavior due to their...

Mössbauer investigations of solid phases that were formed during the reduction of amorphous synthesized ferrihydrite (SF) by thermophilic anaerobic iron-reducing bacterium Thermincola ferriacetica (strain Z-0001) and alkaliphilic anaerobic iron-reducing bacterium Geoalkalibacter ferrihydriticus (strain Z-0531) were carried out at room, liquid nitro...

Magnetic hyperfine fields of Fe 90Zr 7B 3 Nanoperm nanocrystalline alloy are characterized by 57Fe Mössbauer spectrometry and 57Fe NMR as well as by magnetic force microscopy. 57Fe NMR enables to distinguish a broad signal of iron atoms located in a residual amorphous matrix from a narrow one which belongs to Fe in nanograins. The former coincides...

Magnetic and electrical properties of magnetic nanostructures are under intensive study due to their promising technological applications such as magnetic data storage, extra-high-frequency (EHF) switches, photonic materials etc. These nanostructures, either in nanolayered [1] or granular [1-4] form, show giant magnetic resistance (GMR), giant magn...

Mössbauer study of nanogranular ferromagnetic FeCo films is presented. Two ways of production of nanocomposite systems were employed: (i) hollow cathode plasma jet deposition process, and (ii) laser ablation from Fe-Co metallic targets by means of a KrF excimer laser and r.f. magnetron sputtering. Complementary information on the composition of the...

Anaerobic alkaliphilic bacterium of Geoalkalibacter ferrihydriticus type (strain Z‐0531), isolated from a bottom sediment sample from the weakly mineralized soda Lake Khadyn, have been analyzed. The strain uses the amorphous Fe(III)‐hydroxide (AFH) as an electron acceptor and acetate CH 3 COO − as an electron donor. Mössbauer investigations o...

In nanocrystalline Fe90Zr7B3, hyperfine fields belonging to the amorphous residual matrix are distinguished from those of bcc-Fe nanograins by nuclear magnetic resonance spectroscopy on 57Fe nuclei. With this technique, the nanograins located in magnetic domains can be distinguished from those positioned in domain walls. Structural features of core...

Magnetic nanoparticles have promising applications in many areas, for example optics, electronics, biology, medicine, etc. The primary goal of this study was to synthesize nanoparticles of magnetic ɛ-Fe2O3 embedded in amorphous SiO2. The structure and properties of the final product have been found to depend strongly on the initial conditions of pr...

Nanogranular magnetic films were produced by the specially designed UHV plasma-jet system with DC hollow-cathode discharge. We investigated the properties of these ferromagnetic FeCo-AlN films. The samples were studied by nuclear magnetic resonance, Mössbauer spectroscopy, and transmission electron microscopy. The films are composed of nanoparticle...

Nanogranular magnetic films were produced by specially designed UHV plasma-jet system with DC hollow-cathode discharge. We investigated the properties of these ferromagnetic FeCoAlN-based films. The analyses of the samples were additionally complemented by the study of nuclear magnetic resonance (NMR), Mössbauer spectroscopy, magnetic measurements,...

Nowadays, an intensive research of new magnetic materials with high frequency permeability has been stimulated by the demand for electronic devices, such as microinductors, transformers and magnetic recording heads, operating in the GHz-frequency range [1]. Soft magnetic nanogranular films consisting of magnetic grains embedded in an insulating mat...

In this study we have measured 1H relaxation times T1 and T2 of deuterated n-butanol (C4D9OH) in a wide range of temperatures (from 280 K down to 140 K). 1H NMR spectra showed expected gradual line broadening with decreasing temperature, more profound in super- cooled liquid (e.g. below 180 K). The characteristic T1 minimum was found at ca. 240 K....

Magnetite single crystals with Al, Ga and Ti substitutions were measured by means of 57Fe nuclear magnetic resonance (NMR) technique. Satellite structure of NMR spectra well above the Verwey temperature was detected and analyzed to obtain information on the distribution of substituting cations on iron sublattices. It was confirmed that Al and Ti en...

Alcohols with nuclear spins highly polarized due to the polarization transfer from stable nitroxyl radicals are suitable materials for polarized nucleon targets. In this work the ethanol- TEMPO system was studied by 1H and 13C high resolution NMR in a liquid phase. The concentration and temperature dependences of spin-lattice relaxation rates, line...

We present an NMR study of hyperfine felds at 57Fe nuclei in polycrystalline yttrium iron garnet. We measured spectra of 57Fe nuclei situated in tetrahedral and octahedral sites in magnetic domains as well as in domain walls at several temperatures within the range of 4.2-344 K. Comparing the simulated lineshapes to the experimental ones we found t...

57Fe NMR spectra of lutetium iron garnet (LuIG) and yttrium iron garnet (YIG) samples prepared by liquid mix process were measured at 4.2 and 77K. We detected and identified patterns of satellite lines induced by lutetium antisite defects Lu(a) in LuIG and yttrium antisite defects Y(a) in YIG. Frequency shifts of satellite lines induced by Lu(a) we...

We report the NMR spectra of gallium substituted magnetite measured at temperatures 4.2, 77 and 273K. A single crystal of Fe3−xGaxO4, x=0.05 has been prepared by a floating zone technique. The Ga-lines found in the NMR spectrum above Verwey temperature TV∼117K indicate a preferency of Ga substitution into the tetrahedral A-sites. The well-resolved...

Temperature dependence of 57Fe NMR spectra was measured below and around the Verwey transition in Fe3−xAlxO4 (x=0, 0.005, 0.01, 0.02, 0.03) single crystals. All lines of substituted samples were broadened with increasing Al concentration, but we have found no change in their positions. The Verwey temperature TV decreases with increasing Al concentr...

NMR on a gadolinium iron garnet was measured in zero and nonzero external magnetic field at 4.2K. 24 well separated lines of 155Gd and 157Gd nuclei were found in the zero field spectrum. From the spectral line positions we determined the EFG tensor and both isotropic and anisotropic components of hyperfine magnetic interaction on gadolinium nuclei....

57Fe nuclear magnetic resonance spectra of the epitaxial yttrium iron garnet film containing small amount of aluminium were measured at 4.2K in an external magnetic field. Analysis of the data yields us the changes of hyperfine parameters induced by Al. The results are compared with those obtained previously for Ga and Ge substitutions.

Using 55Mn nuclear magnetic resonance (NMR), the magnetic phase separation into antiferromagnetic and ferromagnetic phases was found in Ca0.95La0.05MnO3 manganite. At 4.2K, distinct NMR signals from ferromagnetic domains, antiferromagnetic matrix, and from the domain walls were detected. Predominant relaxation mechanism in the ferromagnetic phase i...

Temperature dependence of 57Fe NMR was measured above the Verwey transition in three Fe3−xAlxO4 (x=0, 0.005, 0.03) single crystals. The satellite lines corresponding to Fe (A) which have a single Al (B) nearest neighbor were detected in the NMR spectra of x=0.005 and 0.03 compounds. Temperature dependence of NMR linewidth for x=0.03 indicates that...

The NMR spectrum of the polycrystalline sample of gadolinium iron garnet enriched by 155Gd isotope (91.6%) was detected. The interpretation of this spectrum consisting of 12 lines gives the values of electric field gradient (EFG) tensor, isotropic part and anisotropic components of hyperfine field on 155Gd nuclei. NMR measurements were accompanied...

NMR spectra on 57Fe nuclei in yttrium iron garnet (YIG) containing Y3+(a) defects and Al3+(d) substitutions were measured in the temperature range 4.2–360 K in zero external magnetic field. The temperature dependencies of satellite lines caused by Y3+(a), Al3+(d) impurities were determined. Theoretical description of the temperature behavior of the...

NMR spectra on Fe-57 nuclei in YIG containing Y3+ (a) impurities were measured in the temperature range 4.2-360K in zero external magnetic field. The temperature dependencies of satellite lines caused by Y3+(a) impurity were determined. Theoretical description of the temperature behavior of the main and satellite lines has been carried out in the f...

The nuclear quadrupole resonance (NQR) on Ba nuclei was studied in four samples of BaBiO3 prepared in different ways and, in addition, in BaPbO3. The spectrum of Ba-137 at T = 4.2 K consists of a relatively broad line centered near 18 MHz for all BaBiO3 samples and near 13 MHz for BaPbO3. The integrated intensity of the Ba-137 resonance in the cera...

The nuclear quadrupole resonance (NQR) on Ba nuclei was studied in four samples of BaBiO3 prepared in different ways and, in addition, in BaPbO3. The spectrum of 137Ba at T=4.2 K consists of a relatively broad line centered near 18 MHz for all BaBiO3 samples and near 13 MHz for BaPbO3. The integrated intensity of the 137Ba resonance in the ceramic...

The NQR on Ba nuclei was studied in four samples of BaBiO3 prepared in different ways and, in addition, in BaPbO3. The spectrum of $^{137}$Ba at T=4.2 K consists of relatively broad line centered near 18 MHz for all BaBiO3 samples and near 13 MHz for BaPbO3. The integrated intensity of $^{137}$Ba resonance in ceramic sample BaBiO3 synthesized at 80...

Using NMR, anisotropy of the hyperfine field on 57Fe nuclei was measured in Y3Fe5O12 with nonmagnetic, trivalent substitutions on d (Ga3+) and a (Y3+ - yttrium antisite defect) sites which are occupied by ferric ions in a pure, stoichiometric system. The measurements were performed by the spin-echo method at liquid helium temperature. Thorough anal...

We report the NQR on Ba nuclei in four samples of BaBiO3 prepared in different ways. The spectra of 137Ba consist of broad line centered near 18 MHz at 4.2 K. The broadening of NQR suggests a local distortions of the crystal structure. The area under the line for ceramic sample BaBiO3 synthesized at 800°C is approximately two times larger comparing...

The magnetism in three polycrystalline samples of the electron doped manganites Ca1-xPrxMnO3 (x=0.025, 0.05, 0.1) was investigated by NMR on 55Mn and 141Pr nuclei, neutron diffraction, and magnetic measurements. In all systems the coexistence of majority antiferromagnetic and minority ferromagnetic phases was found. At 4.2 K distinct NMR signals fr...

Abstract-NMR of 57Fe nuclei was measured in two single crystals of magnetite (temperature of the Verwey transition Tv =121.5 K end 123.9 K) between 4.2 and 442 K. Below Tv twenty four NMR lines were detected. Eight lines correspood to Fe on tetrahedral (A) sites, remaining 16 lines arise from octahedrally coordinated (B) irons. NMR thus confirms th...

The anisotropy of the hyperfine field at iron nuclei in Fe3+ ions on d-sites of YIG substituted by La3+ was studied by 57Fe NMR. The isotropic and anisotropic parts of the hyperfine interaction tensors for iron ions without and with one La3+ ion inthe nearest neighbourhood were found, The change o the arusotropic part of the hyperfine interaction c...

The effect of Gd3+ ions on a local magnetic field at iron nuclei was studied by 57Fe nuclear magnetic resonance (NMR) in iron gamets Y3-xGdxFe5OI2. Differences in resonant frequencies of main lines in pure yttrium iron garnet (YlG) and gadolinium iron garnet (GIG) were compared with the frequency shifts of satellite lines present in the spectra of...

The hyperfine field anisotropy tensors, obtained from analysis of 57Fe NMR spectra for iron sites in various magnetic oxides (barium hexaferrite, lithium spinel, magnetite and yttrium-iron garnet) were used to investigate the relation between the hf anisotropy and surrounding ionic arrangement. While a reasonable correlation has been found when the...

57 Fe NMR spectra were measured on thin films of yttrium iron garnet with divalent (Ca2+) and tetravalent (Ge4+) cation substitutions using the spin echo technique at 4.2 K. A series of Y3-xCaxFe5-xGexO12 samples with 0 ≤ x ≤ was prepared by an epitaxial growth from BaO/B2O3/BaF2 flux on gadolinium gallium garnet substrate. Satellite lines correspo...

57Fe NMR spectra of epitaxial yttrium iron garnet film containing small amount of gallium were measured at 4.2 K in an external magnetic field applied along several directions in the plane of the film. The isotropic part and the anisotropy tensor of the hyperfine interaction of iron on a-sites having Ga3+ as the nearest d-neighbours were deduced fr...