Abstract:Multilayers of Co90Fe10/Pd with different bilayer thicknesses, have been deposited by dc-magnetron sputtering on thermally oxidized Si wafers. Transmission electron microscopy showed that the highly textured crystalline films had columnar structure, while scanning transmission electron microscopy and atomic force microscopy respectively indicated some layer waviness and surface roughness. The magnetic domain structure and perpendicular magnetic anisotropy (PMA) of the Co90Fe10/Pd multilayers were investigated by off-axis electron holography and magnetic force microscopy. The Co90Fe10 layer thickness was the primary factor determining the magnetic domain size and the perpendicular magnetization: both decreased as the thickness increased. The strongest PMA was observed in the sample with the thinnest magnetic layer of 0.45 nm.Keywords: Off-axis Electron Holography, CoFe/Pd Multilayers, Perpendicular Magnetic Anisotropy, Magnetic Domain Structure. Highlight: Multilayers of Co90Fe10/Pd with different bilayer thicknesses were deposited by dc-magnetron sputtering on thermally oxidized Si wafers. Off-axis electron holography investigation confirmed that the Co90Fe10 layer thickness was the primary factor determining the magnetic domain size and the perpendicular magnetic isotropy (PMA): both decreased as the thickness increased.  Other features revealed by (scanning) transmission electron microscopy had little impact on magnetic properties.3

The growth of Co-substituted BaTiO 3 (BTO) films on Ge(001) substrates by molecular beam epitaxy is demonstrated. Energy-dispersive X-ray spectroscopy and transmission electron microscopy images confirm the uniform Co distribution. However, no evidence of magnetic ordering is observed in samples grown for Co concentrations between 2-40%. Piezoresponse force microscopy measurements show that a 5% Co-substituted BTO sample exhibits ferroelectric behavior. First-principles calculations indicate that while Co atoms couple ferromagnetically in the absence of oxygen vacancies, the occurrence of oxygen vacancies leads to locally antiferromagnetically coupled complexes with relatively strong spin coupling. The presence of a significant amount of oxygen vacancies is suggested by x-ray photoelectron spectroscopy measurements. I.

Hardware corrosion on porcelain and glass insulators has occurred on ±800 kV UHVDC transmission lines in China. Iron cap corroded insulators all located at the negative polarity and pin corroded insulators concentrated in positive polarity. The corrosion mechanism is analyzed from the aspect of electrochemistry and the corrosion process is researched by means of spray water simulation tests. Mechanical and electrical characteristics tests and simulation calculation have been done. Test and calculation results indicate that iron cap corrosion can aggravate the contamination accumulation on insulator's surface and decrease the flashover voltage. Pin corrosion can decrease the mechanical strength of insulators. XP-4C type porcelain insulator and electrolytic cell are used to research the influence factors of corrosion rate of hardware. The test resultsshow that the contamination degree on insulators' surface and its component have considerable influence on the corrosion rate. The more serious the degree of contamination is, the faster the corrosion rate is. The sequence of cation that lead to the corrosion rate from fast to slow is K + >Na + >Ca 2+ >Mg 2+ , the sequence for anion is Cl ->SO 4 2->NO 3 -.

We have synthesized nanoscale magnetic compasses with high yield. These ferromagnetic iron carbide nano-particles, which are encapsulated in a pair of parallel carbon needles, change their direction in response to an external magnetic field. Electron holography reveals magnetic fields confined to the vicinity of the bicone-shaped particles, which are composed of few ferromagnetic domains. Aligned magnetically and encapsulated in an acrylate polymer matrix, these nano-compasses exhibit anisotropic bulk magnetic permeability with an easy axis normal to the needle direction, that can be understood as a result of the anisotropic demagnetizing field of a non-spherical single-domain particle. This novel material with orthogonal magnetic and structural axes could be highly useful as magnetic components in electromagnetic wave absorbent materials and magnetorheological fluids.