Value Of Magnetic Moment Research Articles

The first principle study of magnetic properties of Mn2WSn, Fe2YSn (Y=Ti, V), Co2YSn (Y=Ti, Zr, Hf, V, Mn) and Ni2YSn (Y=Ti, Zr, Hf, V, Mn) heusler alloys

The spin polarized electronic band structures, density of states (DOS) and magnetic properties of Mn2WSn, Fe2YSn (Y=Ti, V), Co2YSn (Y=Ti, Zr, Hf, V, Mn) and Ni2YSn (Y=Ti, Zr, Hf, V, Mn) huesler compounds are reported. The calculations are performed by using full-potential linearized augmented plane wave method (FP-LAPW) within density functional theory. The magnetic trend in these compounds is studied using values of magnetic moments, exchange interaction and calculated band gap. The results reveal that Mn2WSn and Ni2VSn show 100% spin polarization, Co2YSn (Y=Ti, Zr, Hf, Mn), Fe2YSn (Y=Ti, V), and Ni2MnSn exhibit metallic nature and Ni2YSn (Y=Ti, Zr, Hf) and Co2VSn show semi-conducting behavior.

Enhancement in Curie temperature of nickel substituted Co–Mn ferrite

Curie temperature of Co0.7−xNixMn0.3Fe2O4 (with X=0.00, 0.05, 0.10 and 0.15) synthesized by the double sintering ceramic method, was recorded by, Lorria Sinha (TCL), dc resistivity (TCR) and dielectric measurement (TCD). Curie temperatures obtained by three various methods are in good agreement with each other. Curie temperature measurements exhibit anomalous increasing trend with increasing nickel content for all the compositions. Three - sublattice model is used to elucidate anomalous behavior as, Neels two - sublattice model fails to explain increase in Curie temperature, even after the replacement of Co2+ ions (3µB) by Ni2+ ions (2µB). Decrease in lattice constant and interionic distances can be probably originated by strengthening of A–B interaction. Enhancement in Curie temperature is observed due to the strengthening of A–B interaction. Values of magnetic moments and interaction between them are not the only reasons for enhancement of Tc but change in their orientation with temperature is also important and therefore analysis of Curie temperature is given on basis of anisotropic energy.

Synthesis and characterization of two quaternary uranium tellurides, RbTiU₃Te₉ and CsTiU₃Te₉.

Black crystals of RbTiU₃Te₉ and CsTiU₃Te₉ have been synthesized at 1223 and 1173 K, respectively, by high-temperature solid-state routes. These compounds crystallize in a new structure type in space group C(2h)²-P2₁/m of the monoclinic system. The structure, which is similar to that of CsTiUTe₅, consists of UTe₂ layers connected into a three-dimensional framework by TiTe₆ octahedra. The expanded UTe₂ layers leave channels that are filled by Rb or Cs atoms. Single-crystal resistivity measurements on CsTiU₃Te₉ are consistent with semiconducting behavior; the calculated activation energy is 0.30(1) eV. X-ray photoelectron spectroscopic measurements on CsTiU₃Te₉ indicate that the compound contains U⁴⁺. From single-crystal magnetic measurements, CsTiU₃Te₉ is consistent with antiferromagnetic coupling between magnetic U atoms. The very low value of the effective magnetic moment of 0.56(2) μ(B) is believed to arise from a coexistence of magnetic and nonmagnetic U atoms.

Magneto-optical properties of Cu1−xZnxFe2O4 nanoparticles

Zn doped CuFe2O4 nanoparticles (CZF NPs) were synthesized by a citric acid assisted sol–gel auto combustion process. The obtained samples were characterized by powder X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), high resolution scanning electron microscopy (HR-SEM), energy dispersive X-ray analysis, UV–Vis diffuse reflectance spectra (DRS), and vibrating sample magnetometer (VSM). XRD results confirmed the formation of cubic spinel-type structure with an average crystallite size in the range of 27–33nm. The variation lattice constants obey the Vegard’s Law. The CZF NPs were evaluated for their magneto-optical characteristics. The CZF NPs exhibit superparamagnetic behavior at room temperature (RT). The average Ms value for CZF NPs is about 57emu/g. The observed magnetic moments of products are in the range of 1.76–2.49μB. The small Mr/Ms ratios (maximum 0.22) specify uniaxial anisotropy in the Cu1−xZnxFe2O4 NPs. The high Ms and magnetic moment values are attributed to cation distribution change. The direct optical band gap (Eg) value of CZF NPs was found as 1.42eV.

Magnetic properties of Cu3.9Fe3.4V6O24 with a lyonsite structure

Magnetic properties of the lyonsite-type phase, Cu3.9Fe3.4V6O24, that has been synthesized by a standard solid-state reaction method, were investigated by dc magnetization and electron paramagnetic resonance (EPR) techniques. Complex magnetic behavior and transition to the antiferromagnetic phase at liquid helium temperature have been revealed by measurements of dc susceptibility in ZFC and FC modes in the 2–300 K temperature range as well as static magnetization in magnetic fields up to 70 kOe. Strong antiferromagnetic interactions in clusters or chains of magnetic ions even at high temperatures has been deduced from the obtained value of the effective magnetic moment that was significantly smaller than expected for nominal valences of iron and copper ions. The presence of antiferromagnetic iron dimers in the high-temperature range, critical slowing down of spin fluctuations on approaching Neel temperature and the existence of magnetically isolated iron ions in the antiferromagnetic phase has been suggested from the temperature dependence of EPR parameters (g-factor, linewidth, integrated intensity) obtained by fitting the experimental spectrum with Lorentzian lineshape.

Synthesis and characterization of metal complexes of Schiff base ligand derived from imidazole-2-carboxaldehyde and 4-aminoantipyrine

The Co(II), Ni(II), Cu(II) and Zn(II) complexes of the Schiff base derived from imidazole-2-carboxaldehyde and 4-aminoantipyrine were synthesized. These compounds were characterized by elemental analysis, IR, mass, 1H NMR, electronic spectra, magnetic moment, molar conductance, thermal analysis, powder XRD and SEM. The analytical data show that the metal to ligand ratio is 1:1. The IR results show that the ligand acts as a bidentate donor coordinating through the azomethine nitrogen and imidazole nitrogen atoms. From the electronic spectra and magnetic moment value predicts the geometry of the complexes. The surface morphology of the compounds was studied by SEM. The compounds were screened for their antibacterial activity and antifungal activity using Kirby Bayer disc diffusion method. The DNA cleavage and superoxide dismutase activities of the compounds were investigated. The anticancer activities of the complexes have been carried out towards HeLa and HCT116 cancer cells.

Magnetic Properties of Off-Stoichiometric Ni-X-In (X=Mn, Fe and Co) Magnetic Shape Memory Alloys by First-Principles Calculations

The magnetic properties of the off-stoichiometric Ni2XIn (X=Mn, Fe, Co) are systematically investigated by means of the first–principles calculations within the framework of the density functional theory (DFT) using the Vienna ab initio software package (VASP). The magnitude of the variation in the Ni moments is much larger than that of Mn in the defective Ni2XIn. The value of the Ni magnetic moment sensitively depends on the distance between Ni and X.

Frenkel electron on an arbitrary electromagnetic background and magnetic Zitterbewegung

We present Lagrangian which implies both necessary constraints and dynamical equations for position and spin of relativistic spin one-half particle. The model is consistent for any value of magnetic moment μ and for arbitrary electromagnetic background. Our equations coincide with those of Frenkel in the approximation in which the latter have been obtained by Frenkel. Transition from approximate to exact equations yields two structural modifications of the theory. First, Frenkel condition on spin-tensor turns into the Pirani condition. Second, canonical momentum is no more proportional to velocity. Due to this, even when μ=1 (Frenkel case), the complete and approximate equations predict different behavior of a particle. The difference between momentum and velocity means extra contribution to spin–orbit interaction. To estimate the contribution, we found exact solution to complete equations for the case of uniform magnetic field. While Frenkel electron moves around the circle, our particle experiences magnetic Zitterbewegung, that is oscillates in the direction of magnetic field with amplitude of order of Compton wavelength for the fast particle. Besides, the particle has dipole electric moment.

Vortex–antivortex dynamics in superconductor-antiparallel magnetic dipoles bilayers

Artificial superconductor (S)/ferromagnet (F) hybrid structures composed by a S film and textured F layer have attracted great interest in the last fifteen years. In the limit of high values of magnetic moments, the ferromagnetic layer filled with magnetic particles (dipoles, nanodiscs, microrings, bars, etc.) can induce spontaneous creation and stabilization of vortex–antivortex (v–av) pairs in the S layer. These v–av molecules interact strongly with external applied currents inducing their annihilation or movement. Despite numerous studies about this subject, only a few of them emphasize the microscopic nature of this phenomena. In this work, the intricate dynamics of v–av molecules birth–death events and how this process influences macroscopic quantities are investigated.

Electronic structure and magnetic properties of graphite intercalated with 3d-metals

Electronic structure and magnetic properties of graphite-based systems with intercalated 3d-transition metal atoms (V, Cr, Mn, Fe, Co, Ni) were calculated ab initio using the density functional theory. The presence of different magnetic states depending on the type of inserted M atoms is revealed for hexagonal P6/mmm and P63/mmc crystall structures. The values of magnetic moments appeared to be governed by the p–d hybridization, and by variations of exchange interactions with intercalation. The results of calculations clearly indicate itinerancy of the 3d-electrons of inserted M atoms.

Complexing Behaviour and Antifungal Activity of N-[(1E)-1-(1H-Benzimidazol-2-yl)ethylidene]morpholine-4-carbothiohydrazide and Related Ligand with Metal Ions

The coordination complexes of bivalent metal ions with N-[(1E)-1-(1H-Benzimidazol-2-yl)ethylidene]morpholine-4-carbothiohydrazide (H2bmctz, H2L-1) and N-[(1E)-1-(1H-Benzimidazol-2-yl)(phenyl)methylidene] morpholine-4-carbothiohydrazide (H2bpmctz, H2L-2) were prepared and their neutral, monoanionic, and dianionic forms of ligands of compositions [M(H2L)X2] (M=CoII,NiII,CuII,ZnII,CdII, orPdII, X=Cl−or Br−, and H2L=H2L-1 or H2L-2), [M(HL)2]nH2O where (M=CoII,CuII,MnII,NiII,ZnIIorCdII, H2L=H2L-1 or H2L-2, andn= 0 or 2), and [MLB]nB (M=CuII,NiII,ZnII,CdII, orPdII, B=H2O, Py, orY-pic,n= 0 andn= 1 if B=H2O for Ni(II) and H2L=H2L-1 or H2L-2) have been characterised by magnetic susceptibility measurements, electrical conductance values, and spectral properties. The magnetic moment value of [M(HL2)] (M=MnII,NiII,FeIIorCuII) type complexes is consistent with high spin octahedral structure while those of [M(H2L)X2] (M=CoII,NiII,CuII,ZnII, orCdII, X=Cl−or Br−) possess five coordinated trigonal bipyramidal geometry. The adduct complexes [MLB]·nB (M=NiII, orCuII, B=H2O, Py, orY-pic) are four coordinated planar and those ofZnIIandCdIIcomplexes [MLB], (H2L=H2L-1 or H2L-2, B=H2O, Py orY-pic) are tetrahedral. These ligands have been suggested to coordinate as tridentate (N N S) donor molecule in complexes of type [M(H2L)X2], [M(HL)2], and [MLB]. The antifungal activity of ligands and some of their metal complexes were studied and it was observed that metal complexes show higher activity than free ligand.

Influence of Hydrogenation on Electronic and Magnetic Properties of PrNi: A First Principles Study

Electronic and magnetic properties of PrNi and PrNi–H have been investigated by using first principles approach. Calculations are performed using full potential linearized augmented plane wave plus local orbitals method including spin-polarization within the frame work of density functional theory. The electronic exchange–correlation energy is described by generalized gradient approximation. The ground state of both the compounds is base-centered orthorhombic CrB structure. The hydrogen stored in PrNi, i.e., PrNi–H has been studied to analyze the effective changes in magnetic moments and electronic structures in comparison with PrNi. The total cell energy of the hydrogenated PrNi compound has been found to be lower than in PrNi compound. The decrease in the cell energy shows more stability of the hydrogenated PrNi at ambient conditions. The values for total and local magnetic moments decrease on hydrogen insertion in PrNi. A comparative study of the projected density of states in both the compounds has also been presented. Both the compounds are found metallic in nature.

Supported iron-based catalysts under influence of static magnetic field for the removal of TBP and EDTA

Zerovalent metals offer decontamination of organic toxins in aqueous medium. In the present study, alumina-based iron and iron–nickel in the presence and the absence of magnetic field for the decontamination of tributyl phosphate (TBP) and ethylene diamine tetraacetic acid (EDTA) has been compared. TBP decontamination was improved in the presence of zerovalent metals. EDTA decontamination was not enhanced in the presence of zerovalent metals. The decontamination of TBP using iron-based alumina was higher than iron–nickel. The surface interaction on alumina surface, as characterized by attentuated total reflectance-Fourier transform infrared spectroscopy, and the surface interaction on metallic elements, as characterized by evaluating the magnetic moment values helped to understand the reason for the difference in role of alumina-based iron and iron–nickel on decontamination of TBP and EDTA.

Antibacterial, DNA interaction and cytotoxic activities of pendant-armed polyamine macrocyclic dinuclear nickel(II) and copper(II) complexes

A series of dinuclear nickel(II) and copper(II) complexes (1–6) of hexaaza macrocycles of 2,6-diformyl-4-methylphenol with three different benzoyl pendant-arms, 2,2′-benzoyliminodi(ethylamine) trihydrochloride (L), 2,2′-4-nitrobenzoyliminodi(ethylamine) trihydrochloride (L′) and 2,2′-3,5-dinitrobenzoyliminodi(ethylamine) trihydrochloride (L″) have been synthesized and characterized by spectral methods. The electrochemical studies of these complexes depict two irreversible one electron reduction processes around E1pc=−0.62 to −0.76V and E2pc=−1.21 to −1.31, and nickel(II) complexes (1–3) exhibit two irreversible one electron oxidation processes around E1pa=1.08 to 1.14V and E2pa=1.71 to 1.74V. The room temperature magnetic moment values (μeff, 1.52–1.54 BM) indicate the presence of an antiferromagnetic interaction in the binuclear copper(II) complexes (4–6) which is also observed from the broad ESR spectra with a g value of 2.14–2.15. The synthesized complexes (1–6) were screened for their antibacterial activity. The results of DNA interaction studies indicate that the dinuclear complexes can bind to calf thymus DNA by intercalative mode and display efficient cleavage of plasmid DNA. Further, the cytotoxic activity of complexes 2, 5 and 6 on human liver adenocarcinoma (HepG2) cell line has been examined. Nuclear-chromatin cleavage has also been observed with PI staining and comet assays.

Synthesis And Characterization Of Thermally Resistant Aromatic Polyamide-metal Complexes

Amino group terminated oligomeric aromatic polyamides were prepared using phosphorylation technique and subsequently converted into Schiff’s base coordination polymers by reaction with Co (II), Ni (II) and Cu (II) complexes of salicyladehyde [M(SAL)2] and 2-hydroxy-1-naphthaldehyde [M(NAPHTHAL)2]. These polyamide metal complexes were characterized by elemental analysis, IR spectroscopy and thermo gravimetric analysis; and an oxygen and nitrogen coordinated structure was inferred. Magnetic moment values of the different products indicated the variation in geometry. Introduction of metal ions into the polyamide chains enhanced the thermal stability of the coordination polymers as compared to the respective polymeric ligands. As an extension of this simple and easy technique, the thermal stability of fibers, films, sheets and blocks of amino group containing polyamides can be increasing by introduction of metal ions through Schiff base formation. These polyamide Schiff base complexes are expected to show promising antimicrobial activities.

Magnetisation and magnetoresistance of Mo/Fe/Co superlattices

AbstractIn this paper, we present experimental studies of the structure, magnetic behavior and magnetoresistance of magnetic superlattices (MSL) [Mo(12Å)Fe(xÅ)Co(21Å)]*100 (x=4÷43). MSLs have been obtained by cathode sputtering with oscillating electrons on the substrate of mica (muscovite). MSLs investigated at room temperature are soft ferromagnets with induced in‐plane magnetic anisotropy. Changes in the spontaneous magnetization Iso and coercive force Hc, depending on the thickness of Co layers, are of oscillatory behavior, which is apparently because of the interference effects of electron waves in the spacers and interfaces. Stepped shape of the measured hysteresis loops for some MSLs, is apparently determined by the vortex behavior of the clusters magnetic moments, located in the sample plane, that is confirmed by measurements carried out on the scanning probe microscope. The observed high values of Iso, normalized to the content of Fe and Co, exceeding Iso(Fe)=1710 Gs may be observed due to increasing values of spin and orbital magnetic moments of Fe and Co in the cluster formations and in the interfaces in the states of low‐dimensional local atomic environment, as well as the possible formation of ferromagnetic order in Mo clusters. Studies of resistance and magnetoresistance (MR) of the samples at temperatures from 10 K to 290 K show semiconducting behavior of resistance and a positive sign of the magnetoresistance. The maximum value of MR for a sample of [Mo (12A) Fe (16A) Co (21A)] x100 was 0.04% for [Mo (12A) Fe (10A) Co (21A)]x100 ‐ 0.5%. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Synthesis, characterization and reactivity of trinuclear Cu(II) complexes derived from disalicylaldehyde malonoyldihydrazone

Three new homotrinuclear copper(II) complexes [Cu3(slmh)(μ-Cl)2(CH3OH)3]⋅0.5CH3OH (1), [Cu3(slmh)(NO3)2(CH3OH)5]⋅1.5CH3OH (2) and [Cu3(slmh)(μ-ClO4)2(CH3OH)3]⋅2CH3OH (3) from disalicylaldehyde malonoyldihydrazone have been synthesized and characterized. The composition of the complexes has been established on the basis of data obtained from analytical and thermoanalytical data. The structure of the complexes has been discussed in the light of molar conductance, electronic, FT-IR and far-IR spectral data, magnetic moment and EPR spectral studies. The molar conductance values for the complexes in DMSO solution indicate that all of them are non-electrolyte. The magnetic moment values for the complexes suggest considerable metal–metal intramolecular interaction between metal ions in the structural unit of the complexes. The EPR spectral features reveal that at RT, the ground state for the complexes is a mixture of the quartet state (S=3/2) and doublet state (S=½). At lower temperature, the ground state for the complexes is dx2−y2 with considerable contribution from dz2 orbital. Dihydrazone ligand is present in enol form in all of the complexes. The complexes have distorted square pyramidal stereochemistry. The electron transfer reactions of the complexes have been investigated by cyclic voltammetry. Hydrogen peroxide mediated oxidation of benzyl alcohol catalyzed by complex 1 has been studied.

GGA+U investigations of impurity d-electrons effects on the electronic and magnetic properties of ZnO

Stimulation of novel features in ZnO by impurity electrons has attracted a remarkable attention of researchers from the past decade. Consequently, ZnO has found several applications in the field of spintronics and optoelectronics. We report, the effect of 3d-(V, Ag) electrons on the properties of ZnO in stable wurtzite (WZ) and metastable zincblende (ZB) phase using the density functional theory. Introduction of V-3d electrons was found to induce a high magnetic moment value of 5.22 in WZ and 3.26 in the ZB phase, and moreover transform the semiconductor character of ZnO into a metallic nature. Ag-d electrons result in the p-type half-metallic nature of ZnO with a weak ferromagnetic background. Our calculations for ground-state magnetic ordering show that ZnO in the presence of impure 3d-(V, Ag) electrons favors ferromagnetic ordering, and obey the double exchange mechanism. However, impurity atoms have very marginal effect on the lattice parameters of ZnO, thereby exposing its potential to absorb the impurity atoms in high concentration.

Synthesis and spectral characterization of copper(II) complexes derived from 2-benzoylpyridine-N4,N4-dimethyl-3-thiosemicarbazone: Crystal structure of a binuclear complex

Six copper(II) complexes [Cu2(L)2SO4]·H2O (1), [Cu2(L)2(OAc)2]·H2O (2), [Cu(L)NO3]2 (3), [Cu(L)N3]2·H2O (4), [Cu(L)NCS]·H2O (5) and [Cu(L)I] (6) of 2-benzoylpyridine-N4,N4-dimethyl-3-thiosemicarbazone (HL) were prepared and characterized using partial elemental analysis, magnetic susceptibility, conductivity measurements, FT-IR, UV–Vis and EPR studies. The molecular structure of [Cu2(L)2(OAc)2] (2a) was resolved using single crystal X-ray diffraction studies and it was found to have distorted square pyramidal geometry with the basal plane occupied by thiosemicarbazone and the acetate oxygen O2. The compound crystallized in monoclinic space group P21/n and formed a centrosymmetric dimer, bridged through oxygen of the acetate moiety. From the physicochemical studies, it was found that thiosemicarbazone coordinates through one of the pyridyl nitrogen, azomethine nitrogen and thioiminolate sulfur atoms. Binuclear nature of some of the complexes was confirmed from EPR parameters and magnetic moment values. In all complexes g values in frozen DMF, indicate the presence of the unpaired electron residing in the dx2−y2 orbital.

Magnetic moments ofΞQ′−ΞQtransitions in light cone QCD

The ${\mathrm{\ensuremath{\Xi}}}_{Q}^{\ensuremath{'}}\text{\ensuremath{-}}{\mathrm{\ensuremath{\Xi}}}_{Q}$ transition magnetic moments are calculated in a framework of the light cone QCD sum rules method. The values of the transition magnetic moments obtained are compared with the predictions of the other theoretical approaches.