Calculation Of Magnetic Susceptibility Research Articles

Electron-Rich MoIV 3 -Polyoxomolybdates Resembling the Paratungstic Archetype.

The first polyoxometalates (POMs) composed of MoIV , MoV 2 , discrete d1 -MoV and MoVI , [MoIV 3 MoV 6 MoVI 4 O32 (μ2 -OH)(μ3 -OH)py9 ] (1), was prepared from the solvothermal partial oxidation of [MoIV 3 O2 (O2 CCH3 )6 (H2 O)3 ]ZnCl4 in a mixture of pyridine and water. The MoV =O adduct-free unit [H2 Mo12 O33 py9 ] presents the 11e-reduced Mo derivative of the paratungtic archetype. The use of methanol, ethanol, n-propyl alcohol and triglycol instead of water produced the isostructural [MoIV 3 MoV 6 MoVI 4 O32 (μ3 -OH)(μ2 -OR)py9 ](R=CH3 , 2; C2 H5 , 3; C3 H7 , 4; C2 H4 OH, 5), providing the first examples of MoIV 3 -POMs containing bridging alkoxyl groups. The addition of [CrIII Mo6 O24 ]9- led to the substitution of {MoV =O}3+ with {CrIII -py}3+ in the allomer [MoIV 3 MoV 5 MoVI 4 CrIII O32 (μ-OH)2 py10 ] (6). Using a mixture of Mo3 and MoW2 precursors afforded WVI -incorporated allomer [MoIV 3 MoV 6 MoVI WVI 3 O32 (μ-OH)2 py9 ] (7). The complete substitution of MoVI with WVI by using a mixture of the Mo2 W, MoW2 and W3 precursors produced the diamagnetic [MoIV 3 MoV 6 WVI 4 O33 (μ3 -OH)py9 ]- (syn-8) resulting from the anti→syn conversion between the top and bottom M3 triads concomitant with MoV -MoV bonding. Both anti-1-7 and syn-8 have been characterized by X-ray single crystal structural analyses. The spin distribution and magnetic interactions have been investigated by temperature-dependent magnetic susceptibility and DFT theoretical calculations. Heterogeneous hydrogen transfer catalysis has been examined by the Lewis catalysis field (LCF) theory.

The magnetic properties of MAl4(OH)12SO4·3H2O with M = Co2+, Ni2+, and Cu2+ determined by a combined experimental and computational approach.

The magnetic properties of the nickelalumite-type layered double hydroxides (LDH), MAl4(OH)12(SO4)·3H2O (MAl4-LDH) with M = Co2+ (S = 3/2), Ni2+ (S = 1), or Cu2+ (S = 1/2) were determined by a combined experimental and computational approach. They represent three new inorganic, low-dimensional magnetic systems with a defect-free, structurally ordered magnetic lattice. They exhibit no sign of magnetic ordering down to 2 K in contrast to conventional hydrotalcite LDH. Detailed insight into the complex interplay between the choice of magnetic ion (M2+) and magnetic properties was obtained by a combination of magnetic susceptibility, heat capacity, neutron scattering, solid-state NMR spectroscopy, and first-principles calculations. The NiAl4- and especially CoAl4-LDH have pronounced zero-field splitting (ZFS, easy-axis and easy-plane, respectively) and weak ferromagnetic nearest-neighbour interactions. Thus, they are rare examples of predominantly zero-dimensional spin systems in dense, inorganic matrices. In contrast, CuAl4-LDH (S = 1/2) consists of weakly ferromagnetic S = 1/2 spin chains. For all three MAl4-LDH, good agreement is found between the experimental magnetic parameters (J, D, g) and first-principles quantum chemical calculations, which also predict that the interchain couplings are extremely weak (< 0.1 cm-1). Thus, our approach will be valuable for evaluation and prediction of magnetic properties in other inorganic materials.

Deconvolution of metal apportionment in bulk metal-organic frameworks.

We report a general route to decipher the apportionment of metal ions in bulk metal-organic frameworks (MOFs) by solid-state nuclear magnetic resonance spectroscopy. We demonstrate this route in Mg1-xNix-MOF-74, where we uncover all eight possible atomic-scale Mg/Ni arrangements through identification and quantification of the distinct chemical environments of 13C-labeled carboxylates as a function of the Ni content. Here, we use magnetic susceptibility, bond pathway, and density functional theory calculations to identify local metal bonding configurations. The results refute the notion of random apportionment from solution synthesis; rather, we reveal that only two of eight Mg/Ni arrangements are preferred in the Ni-incorporated MOFs. These preferred structural arrangements manifest themselves in macroscopic adsorption phenomena as illustrated by CO/CO2 breakthrough curves. We envision that this nondestructive methodology can be further applied to analyze bulk assembly of other mixed-metal MOFs, greatly extending the knowledge on structure-property relationships of MOFs and their derived materials.

Preparation, Characterization of Some Metal Complexes of New Mixed Ligands Derived from 5-Methyl Imidazole and Study the Biological Activity of Palladium (II) Complex as Anticance

A new series of mixed ligand complexes synthesized and characterized using of azo ligand derived from (5-methyl— imidazole) with (8-hydroxy quinolone). New mix-ligand structures and their transitional metal complexes were fully characterized using several techniques, including molar conductance, elemental analysis (C.H.N), electronic spectral, magnetic measurements, 1HNMR, spectral studies, and mass spectra. The data shows that these complexes have a composition of [ML(8-HQ) Cl2] H2O where M = Co(II), Zn(II), Cu(II), X=0, and Ni(II), X=1, [ML(8-HQ)] Cl. where M=Pd. The electronic spectral data and magnetic susceptibility calculations of the complexes indicate that the octahedral geometry of all complexes, except for the Pd(II) complex, indicates a planar-square geometry. The results demonstrate that the nitrogen of the imidazole ring and azo nitrogen atom of the primary ligand are coordination sites with a nitrogen atom and oxygen atom of a secondary ligand of the (8-HQ) in the basic medium. Biological effects of the palladium (II) complex are screening against human breast cancer (MCF-7 and AMJ-13) and normal cells (HBL) were examined, which indicated colon cancer cell line LS-174. The results show the highest activity effect for the complex.

Ferromagnetic Coupling in Oxidovanadium(IV)-Porphyrin Radical Dimers.

Three different oxidovanadium(IV) porphyrin dimers with anti, cis, and trans arrangements of the two rings have been synthesized by changing the bridge between the porphyrin macrocycles. This provides a unique opportunity to investigate the role of the bridge and spatial arrangement between the two VIVO centers for their electronic communication and magnetic coupling. They were characterized by the combined application of XRD analysis, UV-vis and electron paramagnetic resonance (EPR) spectroscopy, cyclic voltammetry, magnetic susceptibility, and DFT calculations. One- and two-electron oxidations produce mono- and dication diradical species, respectively, which display an unusual ferromagnetic interaction between the unpaired spins of vanadium(IV) and porphyrin π-cation radical, in contrast to other metalloporphyrin dimers. The oxidized species show a dissimilar behavior between cis and trans isomers. The ferromagnetic coupling occurs between the porphyrin π-cation radical and the unpaired electron of the VIVO ion on the dxy orbital, orthogonal to the porphyrin-based molecular orbitals a1u and a2u.

Nano-Schiff base Ligand:Synthesis, Characterization, DFT, and Antibacterial Evaluation of Some Complexes Derived From 4-(-4-methoxybenzylidene)amino) -Antipyrinyl with Glycine amino acid ligand

Synthesized from a new Neutral tridentate N2O Schiff base 4-(4- methoxybenzylidene)amino)-1,5-dimethyl-2-phenyl-1,2-dihydro-3H-pyrazol-3-one with amino acid ligand.forms stable complexes with transition metal ions such as Co (II), Ni (II), Cu (II), and Cd (II). The complexes were characterized on the basis of their Elemental analysis, molar conductivity, magnetic susceptibility data, IR, 1H-NMR, UV-Vis, XRD, Thermal Analysis (T.G, DTA, DSC), SEM, and Calculation Theoretical studies(DFT). Were used to characterize the complexes. The ligand acts as a tridentate chelating agent, According to physicochemical and spectral results, the ligand acts as a tridentate chelating agent. IR, UV-Vis., and magnetic susceptibility measurements all refer to an octahedral geometry. The general composition of all complexes [M(L)2] is (M=Co(II), Ni(II),Cu(II) and Cd(II), L=(K4-AMetB-Gly) The studies have led to the conclusion that, The coordination sites were established to be oxygen of the carboxyl COO- and two atoms nitrogen of the azomethine (CH=N) group based on the studies. The complexes non-electrolytic nature is verified by the lower conductivity data. The antibacterial activity of the ligand and its complexes was tested against Staphylococcus aureus, Escherichia coli, Klebsiella, and Psedomonas aeruginosa, it was found that these compounds show different activity of inhibition on the growth of the bacteria.

Calculation of energy and magnetic susceptibility of Fe atomic system during dislocation motion in magnetic field

PurposeThe purpose is to calculate the change in the total energy of a small fragment of an idealized lattice of iron (in its pure form and with impurity atoms) containing an edge dislocation during its elementary motion at one interatomic spacing, both under the influence of a constant magnetic field and without it. The introduction of a magnetic field into the system is aimed at checking the adequacy of the description of the phenomenon of magnetoplasticity by changing the total energy of the atomic system.Design/methodology/approachThe design procedure is based on a quantum-mechanical description of the switching process of the covalent bond of atoms in the dislocation core. The authors used the method of density functional theory in the Kohn-Shem version, implemented in the GAUSSIAN 09 software package. Using the perturbation theory, the authors modeled the impact of an external constant magnetic field on the energy of a system of lattice atoms.FindingsThe simulation results confirmed the effect of an external constant magnetic field on the switching energy of the covalent bond of atoms in the dislocation core, and also a change in the magnetic susceptibility of a system of atoms with a dislocation. This complements the description of the magnetoplastic effect during the deformation of metals.Originality/valueThe authors created quantum-mechanical models of the dislocation motion in the Fe crystal lattice: without impurities, with a substitutional atom Cr and with an interstitial atom C. The models take into account the influence of an external constant magnetic field.

New heterobimetallic Cu(II)/Mn(II) complexes with trans-1,8-cyclam derivatives: Synthesis, characterization, magnetic properties and crystal structures of (µ2-Chloro)-(dpc)-copper(II)-trichloro-manganese(II) and two polymorphs of (µ2-Chloro)-(dac)-copper(II)-trichloro-manganese(II)

Two derivatives of cyclam (cyclam = 1,4,8,11-tetraazacyclotetradecane) with propyl- or allyl- (prop-2-en-1-yl) substituents on nitrogen atoms in trans positions, namely 1,8-dipropyl-1,4,8,11-tetraazacyclotetradecane (dpc) and 1,8-diallyl-1,4,8,11-tetraazacyclotetradecane (dac) were prepared and characterized by IR, 1H NMR and 13C NMR spectroscopy. Reaction of dpc and dac with copper(II) chloride gives compounds [Cu(dpc)(H2O)2]Cl2 (1) and [Cu(dac)(H2O)2]Cl2 (3) with similar crystal structures. Compounds 1 and 3 were used as precursors in the synthesis of Cu(II)/Mn(II) complexes 2, 4a and 4b. Prepared complexes were characterized by IR spectroscopy, elemental analysis and their crystal structures were determined using single crystal X-ray analysis. Compounds 4a and 4b are polymorphs, both crystallize in the monoclinic crystal system and the main difference in their crystal structures is in steric arrangement of metal centres within a chain. Moreover, measurements of magnetic susceptibility and Broken Symmetry DFT calculations (BS DFT calculations) carried out for bimetallic complexes 2 and 4a showed that a ferromagnetic exchange interaction J/kB = 2.28 K and J/kB = 2.34 K, respectively, exists within the dinuclear units.

The crystal-field level scheme of fnJ multiplets under cubic crystal-field with three-fold quantization axis

The effect of crystal-field Hamiltonian with cubic symmetry acting upon different angular momenta J-manifolds between 2 and 8 has been investigated considering the quantization axis along body diagonal [111] axis of the cube. The eigen-values and eigen-functions are numerically computed as a function of the ratio between the fourth and sixth degree terms of the cubic Hamiltonian, expressed in terms of the two parameters, e.g., x and W, in the notation of LLW [J. Phys. Chem. Solids 23 (1962) 1381]. The analytical expressions of eigen-values are also presented for few J values. The effect of external magnetic field as a perturbation on the crystal-field level scheme is discussed toward calculations of magnetic susceptibility and axial magnetizations and compared with the LLW Hamiltonian.

New Platinum (II) Ternary Complexes of Formamidine and Pyrophosphate: Synthesis, Characterization and DFT Calculations and In vitro Cytotoxicity.

Platinum (II) and platinum (IV) of pyrophosphate complexes have been prepared and characterized to discover their potential as antitumor drugs. This study was conducted to prepare and characterize new ternary platinum (II) complexes with formamidine and pyrophosphate as an antitumor candidate. The complexes have been characterized by mass, infrared, UV-Vis. spectroscopy, elemental analysis, magnetic susceptibility, thermal analyses, and theoretical calculations. They have been tested for their cytotoxicity, which was carried out using the fastcolorimetric assay for cellular growth and survival against MCF-7 (breast cancer cell line), HCT- 116 (colon carcinoma cell line), and HepG-2 (hepatocellular cancer cell line). All complexes are diamagnetic, and the electronic spectral data displayed the bands due to square planar Pt(II) complexes. The optimized complexes structures (1-4) indicated a distorted square planar geometry where O-Pt-O and N-Pt-N bond angles were 82.04°-96.44°, respectively. Results also show that all complexes are neutral, stable and non-hygroscopic and have noticeable cytotoxicity with IC50 (μM): 0.035-0.144 MCF-7(breast cancer cell line), 0.042-0.187 HCT-116 (colon carcinoma cell line), and 0.063-0.168 HepG-2 (hepatocellular cancer cell line). Moreover, the results show that the complex (4) has the best IC50 value. The complexes showed noticeable cytotoxicity and are considered as promising antitumor candidates for further applications.

STRUCTURAL STUDY OF COMPLEXES FROM HEXAFLUOROACETYLACETONE, PYRAZOLE, AND ITS PYRAZOLE DERIVATIVE WITH SOME METALS BY FT-IR, AND 1H-NMR

The series complex formation nickel(II) or cobalt(III) with hexafluoroacetylacetone, pyrazole, 3,5-dimethylpyrazole, and 3,5-bis(trifluoromethyl)-1H-pyrazole were prepared. The first reaction step included the synthesis of the complex using hexafluoroacetylacetone as a ligand with Co(III) or Ni(II), metals with high spin with π donate and enol-form of the ligand. This formed complex was identified by FT-IR, 1H-NMR spectroscopy, and magnetic susceptibility calculation. Whereas, the second reaction step to produce the complex depended upon mixing water and pyrazole and using it as ligands with Co(III) or Ni(II) a metal, which is a high spin with one donate and the another is aromatic nitrogen atom in a ligand. In the third reaction step, the complexes were produced by mixing water with 3,5-bis(trifluoromethyl)-1H-pyrazole as a ligand with Co(III) or Ni(II) as low spin metal. The analysis of these prepared complexes and their used ligands were done by comparing the results using 1H-NMR and FT-IR spectroscopies. Besides, the magnetic susceptibility calculation was also employed. The results of 1H-NMR spectroscopy and magnetic susceptibility proved that the produced complexes are diamagnetic when the ligand includes the CF3 group. At the same time, the produced complexes are paramagnetic, when the ligand without the CF3 group, which is formed the mixture of water and 3,5-dimethylpyrazole as ligand or water and pyrazole as a ligand with Co(III) or Ni(II) as metal. All the ligands in the paramagnetic complexes were one donate, and another the donated atom in pyrazol is an aromatic nitrogen atom. Therefore all prepared high spin complexes were not evident in the 1H-NMR spectrum because the peaks appear brood that due to high T1 relaxation 1H-NMR time, and the investigation turned out two assignment peaks. This behavior is an attitude to happen the ketone form and enol form phenomenon by using 1H-NMR spectra, and its an evident assignment coupling between hydrogen or carbon atom with a fluorine atom.

An AI approach to automated magnetic formation mapping beneath cover

SummaryMost regional scale magnetic maps are dominated by the magnetic characteristics of steeply dipping basement units truncated by an unconformity surface. It is easy to demonstrate that 80 to 90% of each total field magnetic anomaly is contributed by this intersecting surface. We approach this problem by mapping the boundaries between contrasting magnetic units along each line in the magnetic survey using the full precision of the line data and 3D information from the magnetic gradient tensor. Additionally, we derive the azimuth of each boundary, depth to the unconformity and magnetic properties of the anomalous units. The segments are overlain on any image such as existing geological maps, satellite imagery, gravity or magnetic imagery to provide a new geological interpretation concept. This method provides a new way to interpret new and old magnetic surveys.Eigenvector analysis of the magnetic tensor and normalised source strength (NSS) are combined with an artificial intelligence (AI) approach to estimate the basement properties. The method is applied to full tensor magnetic survey data or a grid of the total magnetic intensity data is processed using FFT transformations to derive the magnetic gradient tensor. These data are used as input to the pre-trained AI process for calculation of depth, width, azimuth, magnetic susceptibility and magnetisation direction. The rock properties and depth information can be used for 3D visualisation of the unconformity and 2D mapping of the magnetic lithology of the unconformity surface.

Numerical calculation of high frequency magnetic susceptibility in thin nanocrystalline magnetic films

Two numerical micromagnetic methods most suitable for calculation of the high frequency magnetic susceptibility of nanocrystalline thin films were considered in detail. The methods are based on the Landau–Lifshitz equation, linearized around the equilibrium state leading to an eigenvalue problem or solved using an undetermined coefficients technique. An analysis and estimation of an efficiency of the methods were carried out. Several conclusions about their advantages and shortcomings, as well as specifics of their practical application were drawn.

Soluble ruthenium(II) with 3,4-diaminobenzoic acid complexes

New four water-soluble Ru(II) with 3,4-diaminobenzoic acid complexes were synthesized. The complexes have been characterized using different tools such as: elemental analysis, mass, infrared, UV–Vis spectroscopy, magnetic susceptibility, thermal analysis and theoretical calculations. The complexes are diamagnetic and the electronic spectral data showed the peaks due to low-spin octahedral Ru(II) complexes. The thermal studies of complexes were investigated by the thermogravimetric analysis. The derivative thermogravimetric analysis has been also used to describe the steps ranges for better precision. The data showed that all complexes have been decomposed in three steps, and the decomposition data are consistent with the proposed formulae of the complexes. The thermal stability of the complexes (1–4) is confirmed by their relatively high overall activation energy ranged (96–207 kJ mol−1). The optimized structures of complexes (1–4) indicate that the complexes have distorted octahedral geometries with bond angles around the ruthenium atom ranged 78.37°–99.08°. The negative values of the electronic energies (− 807 to − 1319 a.u.), the highest occupied molecular orbital energies (− 0.176 to − 0.215 a.u.) and the lowest unoccupied molecular orbital energies (− 0.094 to − 0.138 a.u.) of the complexes indicate the stability of the complexes. The complexes are polarized as indicated from dipole moment values (5.18–13.33 Debye). All complexes are water soluble, neutral, stable and non-hygroscopic. The complexes have noticeable cytotoxicity with IC50 (µM): 0.017–0.083 (MCF-7), 0.014–0.123 (HCT-116), 0.024–0.126 (PC-3) and 0.013–0.056 (HepG-2). New soluble Ru(II) complexes with 3,4-diaminobenzoic acid (DABA) ligand and different secondary ligands have been synthesized and characterized. The complexes are diamagnetic with distorted low-spin octahedral geometries. The thermal decomposition of complexes was studied and the thermodynamic parameters were evaluated. The IC50 values are in the range (0.013–0.089) μΜ.

Ab initio Study of Ag-Based Fluoroperovskite AgMF3 (M = Co and Ni) Compounds

Ab initio calculations of Ag-based fluoroperovskite AgMF3 (M = Co and Ni) compounds are investigated using the full-potential linearized augmented plane wave method. Wien2k and BoltzTrap codes are used to calculate the different physical properties. The structural parameters of the present compounds are within reasonable agreement with previous calculations. This study shows that AgCoF3 and AgNiF3 are anisotropic, ductile, mechanically and thermodynamically stable␣compounds, where AgCoF3 is found to be stiffer and less compressible than AgNiF3. The spin-polarized electronic band structure illustrates that AgCoF3 is metallic, while AgNiF3 is a semiconductor with indirect (M–Г) band gap energy of 0.43 eV. The bonding force between atoms is found to be mainly ionic with some covalent nature. The total magnetic moment of AgCoF3 (3.04 μ B) is found to be higher than that calculated for AgNiF3 (2.00 μ B). Using the magnetic susceptibility calculations, AgCoF3 is classified as antiferromagnetic, whereas AgNiF3 is a ferromagnetic compound. The calculated static refractive index of AgCoF3 (3.85) and AgNiF3 (3.60) is inversely proportional with the energy band gap. Suitable␣applications are predicted for AgCoF3 and AgNiF3 based on their absorption and reflection properties. Furthermore, beneficial thermoelectric applications are expected for the present compounds due to their large Seebeck coefficient ( $$ S_{{{\rm{AgCoF}}_{ 3} }} = 2.92 \times 10^{3} \,\, \mu {\hbox{V/K}}\,\,{\hbox{and}}\,\,\,S_{{{\rm{AgNiF}}_{3} }} = 2.84 \times 10^{3} \,\,\mu {\hbox{V/K}} $$ ) and their thermoelectric power factor with respect to relaxation time ( $$ S^{2} \sigma /t_{{AgNiF_{3} }} = 1.11 \times 10^{9} \,\,{\hbox{W/K}}^{ 2} \,\,{\hbox{and}}\,\,S^{2} \sigma /t_{{AgNiF_{3} }} = 1.28 \times 10^{11} \,\,{\hbox{W/K}}^{ 2} $$ ).

Spectral and cyclic voltammetric studies of glyceryl guaiacolate drug in pure form and in situ chelation with some different transition metals

An equimolar series of binary complexes of Cr(III), Mn(II), Fe(III), Co(II), Ni(II), Cu(II) and Zn(II) with guaifenesin (glyceryl guaiacolate) (H2L or Gf) have been synthesized. The Gf ligand is deprotonated and coordinated to the metal ion with both oxygen's donor atoms with 1:1 (metal:Gf) ratio and it is determined by micro-analytical technique. The resulting metal chelates of Gf were characterized using the conductivity measurements, FT-IR, Laser Raman, electronic solid reactance, magnetic susceptibility calculation, 1H NMR, TGA and ESR spectral studies. The conductivity measurements confirm that all the metal complexes were non-electrolytic in DMSO except for chromium and iron(III) complexes have an electrolytic behavior. Based on spectral and analytical data octahedral geometry is assigned to the Cr(III), Mn(II), Fe(III), Co(II) and Ni(II) complexes with four coordinated water molecules, but the copper and zinc(II) complexes have square planner molecular geometry with two coordinated water molecules. The general molecular formula of the solid Gf complexes has been found as [M(Gf)(H2O)n]·x·yH2O, where M=Cr(III), Mn(II), Fe(III), Co(II), Ni(II), Cu(II) and Zn(II), n=2 or 4, x=Cl− for (Fe and Cr(III) complexes) and y=3 for (Cr(III) and Ni(II) complexes). The electrochemical reduction of Gf and its complexes were realized on a platinum wire electrode in Britton–Robinson (BR) buffer using the cyclic voltammetric (CV) technique. The effect of functional groups on reduction potential of the Gf was investigated. A general electrochemical reduction mechanism of the compounds is suggested.

New palladium(II) formamidine complexes: Preparation, characterization, theoretical calculations and cytotoxic activity

Binary Pd(II) formamidine complexes formulated as [Pd(L1−4)Cl2] where L = formamidine ligands, were synthesized and characterized using different tools, such as; elemental analyses, mass, infrared spectroscopy, magnetic susceptibility, thermal analysis and DFT calculations. The complexes are diamagnetic and the electronic spectral data showed the peaks due to square planar Pd(II) complexes. The optimized structures of complexes (1–4) indicate a distorted square planar geometry with ClPdCl and NPdN bond angles in the range 83.89°–94.27°. The electronic energies (a.u.) (−553.79 to −763.92) and the highest occupied molecular orbital (−0.223 to −0.250) and lowest unoccupied molecular orbital energies (−0.091 to −0.127) of the complexes were negative in their values indicated the stability of the complexes. The complexes are polarized as indicated from dipole moment values (6.50–15.71 Debye). All complexes are neutral, stable and non-hygroscopic. The complexes have noticeable cytotoxicity with IC50 (μM): 0.0740 (MCF-7), 0.0074–0.0082 (HEP-2), and 0.0119–0.0144 (HepG-2).

Metodika rascheta magnitnoi vospriimchivosti plenok zhelezo-ittrievogo granata s lineinym defektom struktury ti-pa priamoi skvoznoi treshchiny vo vneshnem magnitnom pole

Metodika rascheta magnitnoi vospriimchivosti plenok zhelezo-ittrievogo granata s lineinym defektom struktury ti-pa priamoi skvoznoi treshchiny vo vneshnem magnitnom pole

Visualizing skin effects in conductors with MRI: [formula omitted]Li MRI experiments and calculations

While experiments on metals have been performed since the early days of NMR (and DNP), the use of bulk metal is normally avoided. Instead, often powders have been used in combination with low fields, so that skin depth effects could be neglected. Another complicating factor of acquiring NMR spectra or MRI images of bulk metal is the strong signal dependence on the orientation between the sample and the radio frequency (rf) coil, leading to non-intuitive image distortions and inaccurate quantification. Such factors are particularly important for NMR and MRI of batteries and other electrochemical devices. Here, we show results from a systematic study combining rf field calculations with experimental MRI of 7Li metal to visualize skin depth effects directly and to analyze the rf field orientation effect on MRI of bulk metal. It is shown that a certain degree of selectivity can be achieved for particular faces of the metal, simply based on the orientation of the sample. By combining rf field calculations with bulk magnetic susceptibility calculations accurate NMR spectra can be obtained from first principles. Such analyses will become valuable in many applications involving battery systems, but also metals, in general.

Spin fluctuations, Fermi surface hotspots and nesting in PuCoGa5

ABSTRACTSurprisingly little is known about the mechanism and symmetry of superconducting pairing in PuCoGa5. A common thread with other unconventional superconductors is the presence of spin fluctuations in the normal state, which in this particular case is controlled by strong spin–orbit coupling split bands. The many and anisotropic Fermi surfaces make the guessing of the potential spin-fluctuation nesting vector and resulting symmetry of the pairing function a nontrivial task. To provide much needed guidance for the identification of the pairing symmetry in this multiband superconductor, we perform first-principles based magnetic spin susceptibility calculations to identify the dominant nesting vectors that potentially give rise to interband pairing with nodal d- or s±-wave gap functions.