Search results for "C.M.M."
showing 10 items of 1066 documents
The influence of intergranular interaction on the magnetization of the ensemble of oriented Stoner-Wohlfarth nanoparticles
2008
We consider the influence of interparticle interaction on the magnetization reversal in the oriented Stoner-Wohlfarth nanoparticles ensemble. To do so, we solve a kinetic equation for the relaxation of the overall ensemble magnetization to its equilibrium value in some effective mean field. Latter field consists of external magnetic field and interaction mean field proportional to the instantaneous value of above magnetization. We show that the interparticle interaction influences the temperature dependence of a coercive field. This influence manifests itself in the noticeable coercivity at $T>T_{b}$ ($T_{b}$ is so-called blocking temperature). The above interaction can also lead to a forma…
Magnetotransport properties of epitaxial - and -oriented CeSb thin films
2000
Abstract We present the electronic magnetotransport properties of (1 0 0) - and (1 1 1) -oriented CeSb thin films. The samples were grown epitaxially by molecular beam epitaxy onto sapphire (1 1 2 0) and (0 0 0 1) substrates. The temperature-dependent resistivity is in full correspondence with the behaviour known from bulk material. For (1 0 0) -oriented films the analysis of the temperature and magnetic field-dependent magnetoresistivity results in a H/T phase diagram analogous to that of bulk samples. For (1 1 1) -oriented films slight deviations were observed. In Hall-effect measurements of (1 0 0) -oriented samples a sign change of the Hall coefficient occurred which is in contrast to m…
Epitaxial films of the magnetic shape memory material
2007
Abstract By DC-sputtering from a stoichiometric target onto sapphire substrates we prepared epitaxial films of Ni 2 MnGa . X-ray diffraction in two circle geometry shows only the Ni 2 MnGa peaks corresponding to a (1 1 0) oriented growth on the (1 1 0) oriented sapphire substrate. Rocking curve scans shows that the out of plane orientation has a width of only 1 . 1 ∘ . By four circle X-ray diffraction we find an in-plane aligned growth. The Curie temperature as determined by SQUID magnetometry is 368 K. On cooling down the low field magnetization drops at around 260–280 K indicating the austenite to martensite transition. The presence of two different phases at high and low temperature also…
Overview on Induced Chirality in Magnetic Field Controlled Electro-Deposition and Induced Magnetic Moment Originating from Chiral Electrodes
2018
Magneto-electrochemistry (MEC) is a unique paradigm in science, where electrochemical experiments are carried out as a function of an applied magnetic field, creating a new horizon of potential scientific and technological applications. Over the time, detailed understanding of this research domain was developed to identify and rationalize the possible effects exerted by a magnetic field on the various microscopic processes occurring in an electrochemical system, such as: electrolyte properties governed by charge-transfer process (electric conductivity, viscosity, and diffusivity), mass transfer, electrochemical kinetics and on the structure/quality of products formed either at the working e…
Oxygen on Fe(110): magnetic properties of the adsorbate system
1999
Abstract Investigations concerning the electronic and magnetic properties of oxygen adsorbed on magnetized iron films were carried out by means of angle and spin resolving photoelectron spectroscopy. Iron(1 1 0), epitaxially grown on a W(1 1 0) crystal, served as the ferromagnetic substrate. Exchange splittings of the O 2p x derived level were detected demonstrating a magnetic coupling between the chemisorbate and the iron layer. This observation indicates the presence of an induced magnetic moment within the adsorbate overlayer. Variations of the exchange splitting occurred as a function of the oxygen coverage, energy of the exciting radiation, and detection angle of the emitted photoelect…
Magnetism of Co-doped ZnO thin films
2007
We have investigated magnetic and transport properties of 5% Co-doped and undoped ZnO thin films deposited on $r$ plane ${\mathrm{Al}}_{2}{\mathrm{O}}_{3}$ substrates by pulsed laser deposition. The Co doped films showed paramagnetic and ferromagnetic behavior as well as a high magnetoresistance and a small anomalous Hall effect. In a range of $0\phantom{\rule{0.3em}{0ex}}\text{to}\phantom{\rule{0.3em}{0ex}}5\phantom{\rule{0.3em}{0ex}}\mathrm{T}$ at low temperatures we observed a double sign change of the magnetoresistance. For undoped ZnO films, prepared by the same conditions, only a negative MR was observed, but surprisingly also a very small anomalous Hall effect. We explain our results…
Polarized neutron reflectivity from monolayers of self-assembled magnetic nanoparticles
2015
We prepared monolayers of iron oxide nanoparticles via self-assembly on a bare silicon wafer and on a vanadium film sputter deposited onto a plane sapphire substrate. The magnetic configuration of nanoparticles in such a dense assembly was investigated by polarized neutron reflectivity. A theoretical model fit shows that the magnetic moments of nanoparticles form quasi domain-like configurations at remanence. This is attributed to the dipolar coupling amongst the nanoparticles.
Influence of the pyrazine substituent on the structure and magnetic properties of dicyanamide-bridged cobalt(ii) complexes.
2019
Substituted pyrazines were successfully used to prepare two new coordination polymers of formulas {[Co(dca)2(NH2pyz)2]·H2O}n (1) and [Co3(dca)6(HOpyz)5(H2O)2]n (2) [dca = dicyanamide, NH2pyz = 2-aminopyrazine and HOpyz = 2-hydroxypyrazine] whose structures were determined by single-crystal X-ray crystallography. The structure of 1 consists of a two-dimensional rhombus grid of cobalt(II) ions where the dca ligand adopts the μ1,5 bridging mode with trans-positioned monodentate NH2pyz molecules completing the six-coordination around each metal ion. Compound 2 exhibits a stair-like two-dimensional structure where the intralayer connections are performed by the dca and HOpyz groups exhibiting μ1…
Effect of antisite defects on the magnetic properties of ZnFe2 O4
2013
Magnetic zinc ferrite (ZnFe2O4) nanopowders were synthesized using the sol–gel autocombustion method. X-ray diffraction (XRD) and scanning electron microscopy (SEM) measurements demonstrated that thermal decomposition of the 1-mm-thick xerogel layers in air formed monophasic spinel ferrite nanopowders with a particle size less than 30 nm. X-ray photoelectron spectroscopy (XPS) showed that the obtained reaction product contained antisite defects, with zinc ions occurring at the octahedral sites of the spinel structure. The concentration of antisite defects or inversion degree decreased when the relatively low annealing temperature was increased from 150 to 500 °C. Overall, the obtained ZnFe2…
Properties of the quaternary half-metal-type Heusler alloyCo2Mn1−xFexSi
2006
This paper reports on the bulk properties of the quaternary Heusler alloy Co2Mn1�xFexSi with the Fe concentration x =0,1/2,1. All samples, which were prepared by arc melting, exhibit L21 long-range order over the complete range of Fe concentration. The structural and magnetic properties of the Co2Mn1�xFexSi Heusler alloys were investigated by means of x-ray diffraction, high- and low-temperature magnetometry, Mossbauer spectroscopy, and differential scanning calorimetry. The electronic structure was explored by means of highenergy photoemission spectroscopy at about 8 keV photon energy. This ensures true bulk sensitivity of the measurements. The magnetization of the Fe-doped Heusler alloys …