Search

A series of thin layers of cobalt are deposited on GaAs semiconductor substrate, using thermal heating process, under a pressure of 10 mbar. The thickness ranges from 18 to 250 nm, values determined by X-ray reflectivity (XRR) technique, and monitored by Rigaku X-ray diffractometer. The hysteresis loops are performed by means of Physical Property Measurement System (PPMS) with Quantum Design Instrument. All the samples are polycrystalline and present a hexagonal close-packed (hcp) structure, some films being under stress. The hysteresis loops display magnetization curves for ferromagnetic samples with the easy axis in the plane of the film. Coercivity seems to depend closely on surface roughness and crystallite size. The lowest value of H, equals to 13 Oe, is related to the smoothest film with a raw mean square (rms) value equal to 0.1 nm, and the smallest stress (0.33 %). Samples with larger crystallites size have larger coercive fields. [ABSTRACT FROM AUTHOR]

This study investigates microwave absorption properties of Ba-hexaferrite (BaFeO) and titanium dioxide (TiO) particles coated with conducting polymer (PANI) and BaFeO-TiO mixture in the frequency range of 8-18 GHz. Samples having different magnetic to dielectric mass ratios and various thicknesses from 1.5 to 4 mm have been prepared to investigate effect of magnetic and dielectric fillers together with influence of conducting polymer layer on microwave absorption properties of BaFeO-TiO composite. Structural, magnetic, and microwave absorption properties of composites have been investigated using X-ray diffraction, scanning electron microscopy and near field microwave measurements using vector network analyzer. Microwave measurements revealed that composites with PANI coating have much higher absorption values which are independent of an absorber thickness. Among PANI coated absorbers, sample having magnetic to dielectric mass ratio of 2 showed better microwave properties in 8-18 GHz range. [ABSTRACT FROM AUTHOR]

The results of structural and ferromagnetic resonance (FMR) investigations of epitaxial half- metallic chromium dioxide (CrO) thin films of thicknesses between 58 nm and 540 nm grown by chemical vapor deposition (CVD) on (100) and (110)-oriented TiO single crystal substrates are presented. The angular dependences of the FMR spectra in different experimental geometries were obtained. Effective magnetic anisotropies of epitaxially grown CrO films of different thicknesses on strain and strain-free surfaces of TiO substrates were estimated. The results indicate that the magnetic behavior of the CrO films results from a competition between the magnetocrystalline and strain anisotropies. It has been revealed that the strain anisotropy dominates in the films grown onto (100)-oriented TiO substrates. On the contrary, the films grown onto (110)-oriented substrates demonstrate strain-free magnetic anisotropy behavior. [ABSTRACT FROM AUTHOR]

Nickel nanoparticles on mass production scale have been prepared using a modified polyol process with Ni(CHCOO)⋅4HO, NaOH, 1,2 propandiol and hydrazinium hydroxide (NH∗HO). A mixture of face centered cubic (fcc) metallic nickel nanoparticles with 12 nm diameter were obtained. We have experimentally studied the structure of nanoparticle by X-ray and Scanning Electron Microscopy (SEM, EDS). The magnetic properties of the prepared Ni film have been studied by Ferromagnetic Resonance (FMR) technique, Vibrating Sample Magnetometer (VSM) and Vector Network Analyzer (VNA). The effective g-factor and magnetic anisotropy constant were determined as g=2.25 and K=85 Oe, respectively. [ABSTRACT FROM AUTHOR]

Multifrequency N nuclear quadrupole resonance (NQR) signals induced due to irradiation by two-frequency composite pulses have been studied. The experiments have been performed on RDX explosive at room temperature. It has been shown that the NQR signal at the observed transition can be essentially enhanced by use of the two-frequency composite pulses. Moreover, it is possible to excite and maintain the precession signal at the third, nonirradiated frequency. We have also shown that the two-frequency composite pulse can be applied as the preparatory pulse for increasing the NQR signal in multipulse sequences. [ABSTRACT FROM AUTHOR]

The article focuses on a collection of papers on chemistry and physics of nanoscale systems, which were presented at the International Conference on Nanoscale Magnetism (ICNM-2010) held in Gebze-Istanbul, Turkey on September 28-October 2, 2010. It says that the specific material in macroscopic scale has a limited number of physical parameters having certain values. It mentions that the role of nanoscale magnetism is important, particularly for higher data-recoding densities.