Nanometer surface roughness effect on the magnetic properties of CoFeHfO thin films.

This article reports the effects of nanometer surface roughness on the magnetic properties of CoFeHfO thin films, as deposited on Si (100) substrates. The surface roughness was controlled via the working pressure during the sputtering time. When the working pressure increases from 0.5 to 3 mT, the surface roughness (R) of CoFeHfO thin films, formed by islands with the average high R, increases from 0.25 nm to 4.66 nm, respectively. At surface roughness (R) = 4.66 nm, coercivity (H(c)) reaches the highest value of 0.42 Oe and magnetic anisotropy (H(k)) drops to the lowest value of 33 Oe. This suggests that the quality of the soft magnetic properties of thin film decrease due to the increase in surface roughness. However, at very low working pressure, thin films become a homogeneous structure which also exhibits poor soft magnetic properties. The optimum value, with H(c) of 0.10 Oe and H(k) of 50 Oe, were obtained at 1.5 mT of working pressure. The model of the roughness effect on the magnetic properties is introduced and discussed.

Effect of Transition Elements on the Thermal Stability of Glassy Alloys 82Al-16Fe-2TM (TM: Ti, Ni, Cu) Prepared by Mechanical Alloying.

In the present study, the thermal stability and crystallization behavior of mechanical alloyed metallic glassy Al82Fe16Ti2, Al82Fe16Ni2, and Al82Fe16Cu2 were investigated. The microstructure of the milled powders was characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), and differential scanning calorimetry (DSC). The results showed remarkable distinction in thermal stability of the alloys by varying only two atomic percentages of transition elements. Among them, Al82Fe16Ti2 alloy shows the highest thermal stability compared to the others. In the crystallization process, exothermal peaks corresponding to precipitation of fcc-Al and intermetallic phases from amorphous matrix were observed.