Search results for "Magnetization"
showing 10 items of 550 documents
A Series of MIICuII3 Stars (M = Mn, Ni, Cu, Zn) Exhibiting Unusual Magnetic Properties
2014
The work in this report describes the syntheses, electrospray ionization mass spectromtery, structures, and experimental and density functional theoretical (DFT) magnetic properties of four tetrametallic stars of composition [M(II)(Cu(II)L)3](ClO4)2 (1, M = Mn; 2, M = Ni; 3, M = Cu; 4, M = Zn) derived from a single-compartment Schiff base ligand, N,N'-bis(salicylidene)-1,4-butanediamine (H2L), which is the [2 + 1] condensation product of salicylaldehyde and 1,4-diaminobutane. The central metal ion (Mn(II), Ni(II), Cu(II), or Zn(II)) is linked with two μ2-phenoxo bridges of each of the three [Cu(II)L] moieties, and thus the central metal ion is encapsulated in between three [Cu(II)L] units. …
Asymmetric bis-(μ1,1-azido) bridged dinuclear copper(II) complex with N2O donor Schiff base: synthesis, structure and magnetic study
2015
A copper(II) complex, [Cu2(L)2(N3)2] [where HL = 2-((3-(methylamino)propylimino)methyl)-6-methoxyphenol] has been synthesized and characterized by elemental analysis, IR, UV–vis and fluorescence spectroscopy, and single-crystal X-ray diffraction studies. The complex crystallizes in the trigonal space group R. The deprotonated tridentate Schiff base occupies three coordination sites of copper(II). The fourth coordination site is occupied by an azide. A symmetry-related azide from a different molecule coordinates with the fifth site of copper(II), thereby forming a double end-on azide-bridged centrosymmetric dimer. Variable temperature solid–state magnetic studies between 2 and 300 K were car…
{CoIIIMnIII}ncorrugated chains based on heteroleptic cyanido metalloligands
2015
The use of the cyanide-bearing complexes PPh4[CoIII(4,4′-dmbipy)(CN)4] and PPh4[CoII(dmphen)(CN)3] as metalloligands towards [Mn(salen)(H2O)]ClO4 affords one-dimensional coordination polymers with the formulas {[MnIII(salen)(μ-NC)2CoIII(4,4-dmbipy)(CN)2]·H2O}n (1) and {[MnIII(salen)(μ-NC)2CoIII(dmphen)(CN)2]}n (2) [PPh4+ = tetraphenylphosphonium cation, 4,4′-dmbipy = 4,4′-dimethyl-2,2′-bipyridine, dmphen = 2,9-dimethyl-1,10-phenanthroline and H2salen = N,N′-ethylenebis(salicylideneimine)]. Compounds 1 and 2 were structurally characterized. Their structures consist of neutral chains with regular alternating [Mn(salen)]+ and [CoIII(4,4′-dmbipy)(CN)4]− (1)/[CoIII(dmphen)(CN)4]− (2) moieties, t…
Magnetic Langmuir-Blodgett films of ferritin with different iron contents.
2006
Magnetic Langmuir-Blodgett films of four ferritin derivatives with different iron contents containing 4220, 3062, 2200, and 1200 iron atoms, respectively, have been prepared by using the adsorption properties of a 6/1 mixed monolayer of methyl stearate (SME) and dioctadecyldimethylammonium bromide (DODA). The molecular organization of the mixed SME/DODA monolayer is strongly affected by the presence of the water-soluble protein in the subphase as shown by pi-A isotherms, BAM images, and imaging ellipsometry at the water-air interface. BAM images reveal the heterogeneity of this mixed monolayer at the air-water interface. We propose that the ferritin is located under the mixed matrix in thos…
Spontaneous Magnetization in Ni−Al and Ni−Fe Layered Double Hydroxides
2008
Layered double hydroxides containing paramagnetic Ni (II) and diamagnetic/paramagnetic Al (III)/Fe (III) ions have been prepared and characterized. Ni 2Al(OH) 6(NO 3). nH 2O ( 1), Ni 2Fe(OH) 6(NO 3). nH 2O ( 2), Ni 2Fe(OH) 6(C 6H 8O 4) 0.5. nH 2O ( 3), and Ni 2Fe(OH) 6(C 10H 16O 4) 0.5. nH 2O ( 4) were prepared by coprecipitation at controlled pH as polycrystalline materials with the typical brucite-like structure, with alternating layers of hydroxide and the corresponding anions, which determine the interlayer separation. Magnetic studies show the appearance of spontaneous magnetization between 2 and 15 K for these compounds. Interestingly, the onset temperature for spontaneous magnetizati…
Element-specific ferromagnetic resonance in epitaxial Heusler spin valve systems
2011
Time-resolved x-ray magnetic circular dichroism was used to investigate epitaxial MgO(100)/Co2Cr0.6Fe0.4Al and MgO(100)/Co2Cr0.6Fe0.4Al/Cr/CoFe films. The precessional motion of the individual sublattice magnetization, excited by continuous microwave excitation in the range 2–10 GHz, was detected by tuning the x-ray photon energy to the L 3 absorption edges of Cr, Fe and Co. The relative phase angle of the sublattice magnetization's response is smaller than the detection limit of 2°. A weakly antiferromagnetically coupled CoFe layer causes an increase in the ferromagnetic resonance linewidth consisting of a constant offset and a component linearly increasing with frequency that we partly at…
Magnetic behavior control in niccolite structural metal formate frameworks [NH2(CH3)2][Fe(III)M(II)(HCOO)6] (M = Fe, Mn, and Co) by varying the dival…
2010
By changing template cation but introducing trivalent iron ions in the known niccolite structural metal formate frameworks, three complexes formulated [NH(2)(CH(3))(2)][Fe(III)M(II)(HCOO)(6)] (M = Fe for 1, Mn for 2, and Co for 3) were synthesized and magnetically characterized. The variation in the compositions of the complexes leads to three different complexes: mixed-valent complex 1, heterometallic but with the same spin state complex 2, and heterometallic heterospin complex 3. The magnetic behaviors are closely related to the divalent metal ions used. Complex 1 exhibits negative magnetization assigned as Neel N-Type ferrimagnet, with an asymmetric magnetization reversal in the hysteres…
A family of enneanuclear iron(II) single-molecule magnets.
2008
Complexes [Fe 9 (X) 2 -(02CMe)8{(2-py) 2 CO 2 } 4 ] (X - = OH (1), N 3 - (2), and NCO- (3)) have been prepared by a route previously employed for the synthesis of analogous Co 9 and Ni 9 complexes, involving hydroxide substitution by pseudohalides (N 3 - , NCO-). As indicated by DC magnetic susceptibility measurements, this substitution induced higher ferromagnetic couplings in complexes 2 and 3, leading to higher ground spin states compared to that of 1. Variable-field experiments have shown that the ground state is not well isolated from excited states, as a result of which it cannot be unambiguously determined. AC susceptometry has revealed out-of-phase signals, which suggests that these…
Theory of the evaporation/condensation transition of equilibrium droplets in finite volumes
2003
Abstract A phenomenological theory of phase coexistence of finite systems near the coexistence curve that occurs in the thermodynamic limit is formulated for the generic case of d-dimensional ferromagnetic Ising lattices of linear dimension L with magnetization m slightly less than mcoex. It is argued that in the limit L→∞ an unconventional first-order transition occurs at a characteristic value mt
Interfaces in the confined Ising system with competing surface fields
2005
Abstract When a magnetic Ising film is confined in a L × M geometry ( L ⪡ M ) short-range competing magnetic fields ( h 1 ) are applied at opposite walls along the M -direction, a (weakly rounded) localization–delocalization transition of the interface between domains of different orientation that runs parallel to walls can be observed. This transition is the precursor of a wetting phase transition that occurs in the limit of infinite film thickness ( L → ∞ ) at the critical curve T w ( h 1 ) . For T T w ( h 1 ) ( T > T w ( h 1 ) ) such an interface is bound to (unbound from) the walls, while right at T w ( h 1 ) the interface is freely fluctuating around the center of the film. We present …