Search results for "Coercivity"
showing 10 items of 74 documents
Magnetic and structural properties of the double-perovskite Ca2FeReO6
2002
Abstract We suceeded in the preparation of polycrystalline Ca2FeReO6 which has a Curie temperature TC of 540 K, the highest value of all magnetic perovskites investigated till now. This material has been characterised by X-ray and neutron powder diffraction. We found at 548 K, a monoclinic unit cell (space group P21/n) with a=5.4366(5) A , b=5.5393(5) A , c=7.7344(5) A , and β=90.044(4)°. For temperatures below 400 K, a phase separation in two monoclinic phases with identical cell volume is observed in neutron scattering. The two phases possess different magnetic structure and coercivity. The conductivity is thermally activated for all temperatures and no significant magnetoresistivity is o…
Magnetic and magnetoelastic properties of epitaxial (2 1 1)-oriented RFe2 (R=Dy, Tb) thin films
2005
Abstract Epitaxial, (2 1 1)-oriented thin films of RFe 2 (R: rare earth; here: Dy, Tb) were deposited by molecular beam epitaxy on faceted and non-faceted α - Al 2 O 3 ( 1 0 1 ¯ 0 ) (m-plane) substrates utilizing a 15 A thin Fe seed layer and a 500 A Nb buffer layer. Detailed X-ray diffraction analyses revealed a twin-free epitaxial (2 1 1)-oriented growth of buffer layer and film. The magnetostrictive layer RFe 2 , as well as the template layers Nb and Mo exhibited the same crystallographic in-plane orientation with regard to the substrate. The same epitaxial relationship was found for films prepared on faceted and on non-faceted substrates. This implies a coherent crystal overgrowth of th…
Pre- and post-synthetic modulation of the ordering temperatures in a family of anilato-based magnets
2019
We report the synthesis and characterization of six novel heterometallic molecule-based 2D magnets with the bromanilato ligand (C6O4Br22− = 1,3-dibromo-2,5-dihydroxy-1,4-benzoquinone dianion) and six different benzene derivative molecules. The compounds, formulated as (NBu4)[MnCr(C6O4Br2)3]·1.75C6H5Br (1), (NBu4)[MnCr(C6O4Br2)3]·C6H5X with X = Cl (2), I (3) and CH3 (4) and (NBu4)[MnCr(C6O4Br2)3]·2C6H5X with X = CN (5) and NO2 (6), present the classical hexagonal honeycomb-(6,3) lattice with alternating Mn(II) and Cr(III) ions. The layers are packed in an eclipsed way along the a direction giving rise to hexagonal channels where the benzene derivative molecules are located with π–π interacti…
Fabrication and characterization of magnetic FePt nanoparticles prepared by extraction–pyrolysis method
2018
We are grateful to Prof. E. Kotomin for useful discussions. The research leading to these results has received funding from the ERAF (2017) Project, while A. I. Popov thanks IMIS-2 for the funding support.
Dielectric and Ferroelectric Properties of Lead-Free NKN and NKN-Based Ceramics
2011
Lead-free ceramics of Na0.5K0.5NbO3 (NKN), Na0.5K0.5(Nb0.94Sb0.06)O3 (NKNS6) and Na0.5K0.5(Nb0.94Sb0.06)O3 + 0.5%MnO2 (NKNS6 + 0.5%MnO2) have been prepared by a solid phase hot pressing sintering process. X-ray diffraction results show that the obtained samples possess the perovskite structure. The micrograph of the fractured surface showed a dense structure in a good agreement with that of 91–94% relative density determined by the Archimedes method. An average grain size decreases with Sb and Mn doping (from about 20 μm for NKN to about 5 and 2 μm for NKNS6 and NKNS6 + 0.5%MnO2, respectively). Low frequency (100 Hz–200 kHz) investigations revealed the diffuse phase transitions. It was foun…
Hydrothermal Synthesis of Cobalt Ferrite Nanosized Powders
2015
Cobalt ferrite powders are synthesized by the co-precipitation technology, combined with the hydrothermal synthesis method and crystallite size, specific surface area (SSA), magnetic properties of synthesized products are obtained. All the synthesized ferrites are nanocrystalline single phase materials with crystallite size of 10-16 nm the SSA of 60±5 m2/g and the calculated particle size of 20±2 nm. Synthesized Co ferrites are characterized by the saturation magnetization MS of 59-60 emu/g, remanent magnetization Mr of 23 emu/g and coercivity Hc of 570-650 Oe.
Photo-induced magnetic bistability in a controlled assembly of anisotropic coordination nanoparticles.
2011
International audience; Anisotropic coordination nanoparticles of the photomagnetic network Cs(I)(2)Cu(II)(7)[Mo(IV)(CN)(8)](4) are obtained through a surfactant-free high-yield synthetic procedure in water. These particles are organised as Langmuir-Blodgett films with a preferential orientation of the nano-objects within the film that exhibit a magnetic bistability below 20 K with a very large coercivity due to an efficient photo-transformation.
Strain-controlled domain wall injection into nanowires for sensor applications
2021
We investigate experimentally the effects of externally applied strain on the injection of 180$^\circ$ domain walls (DW) from a nucleation pad into magnetic nanowires, as typically used for DW-based sensors. In our study the strain, generated by substrate bending, induces in the material a uniaxial anisotropy due to magnetoelastic coupling. To compare the strain effects, $Co_{40}Fe_{40}B_{20}$, $Ni$ and $Ni_{82}Fe_{18}$ samples with in-plane magnetization and different magnetoelastic coupling are deposited. In these samples, we measure the magnetic field required for the injection of a DW, by imaging differential contrast in a magneto-optical Kerr microscope. We find that strain increases t…
Characterization and magnetic properties of nanoparticles based on FePt solid solution with an oxide shell
2015
Abstract We present the results of magnetic properties investigations of ferromagnetic nanoparticles which ensembled with ferromagnetic shell. The aim of this work is to study the connection of structure–phase composition and thermal treatment with the magnetic properties, partially, with the coercive force and the exchange bias field in a two-dimension spin system of core–shell type. It is found that the exchange bias field increases with the growth of the oxide shell thickness. This is realized by annealing in a dosed oxygen flow. The decrease of the coercive force with the increase of annealing temperature is connected with the concentration effect (the concentration of ferromagnetic par…
ANNEALING EFFECT ON COERCIVITY AND MICROHARDNESS IN SINTERED (Nd, Tb)15(Fe, Co, Al)78B7 MAGNETS
1999
The variation of the coercivity and microhardness with annealing (475–1150°C/3.6 ks) of sintered (Nd, Tb) 15 (Fe, Co, Al) 78 B 7 permanent magnet have been investigated. The data indicate that the coercivity reaches the mininum and the maximum at 600°C and 775°C, respectively. Optical and scanning electron microscopy and magnetic domain structure observations give no hints to any change in microstructure. Fitting of the Mössbauer spectra of permanent magnets for different coercivity ( i H c ) values revealed that magnetic hyperfine fields (B Hf ) on all Fe sites are reduced with the increase in i H c value and the higher value of the i H c corresponds to the higher value of the Mössbauer l…