ترغب بنشر مسار تعليمي؟ اضغط هنا

Thermally activated processes of the phase composition and structure formation of the nanoscaled Co-Sb films

33   0   0.0 ( 0 )
 نشر من قبل Attila Csik
 تاريخ النشر 2017
  مجال البحث فيزياء
والبحث باللغة English




اسأل ChatGPT حول البحث

It is investigated the formation of the phase composition and structure in the nanoscaled CoSbx (30 nm) films deposited by the method of molecular-beam epitaxy on the substrates of the oxidated monocrystalline silicon at 200 C and following thermal treatment in vacuum in temperature range of 300-700 C. It is established that the films after the deposition are polycrystalline without texture. With increase in Sb content the formation of the phase composition in the films takes place in such sequence as this is provided by phase diagram for the bulky state of the Co-Sb system. At annealing in vacuum at temperature above 450-500 C a sublimation not only of the crystalline Sb phase but from the antimonides occurs.

قيم البحث

اقرأ أيضاً

We propose a ``multifractal stress activation model combining thermally activated rupture and long memory stress relaxation, which predicts that seismic decay rates after mainshocks follow the Omori law $sim 1/t^p$ with exponents $p$ linearly increas ing with the magnitude $M_L$ of the mainshock and the inverse temperature. We carefully test this prediction on earthquake sequences in the Southern California Earthquake catalog: we find power law relaxations of seismic sequences triggered by mainshocks with exponents $p$ increasing with the mainshock magnitude by approximately $0.1-0.15$ for each magnitude unit increase, from $p(M_L=3) approx 0.6$ to $p(M_L=7) approx 1.1$, in good agreement with the prediction of the multifractal model.
148 - E. Haltz , R. Weil , J. Sampaio 2018
Ferrimagnetic TbFe or TbFeCo amorphous alloy thin films have been grown by co-evaporation in ultra-high vacuum. They exhibit an out-of-plane magnetic anisotropy up to their Curie temperature with a nucleation and propagation reversal mechanism suitab le for current induced domain wall motion. Rutherford back scattering experiments confirmed a fine control of the Tb depth-integrated composition within the evaporation process. However, a large set of experimental techniques were used to evidence an interface related contribution in such thin films as compared to much thicker samples. In particular, scanning transmission electron microscopy experiments evidence a depth dependent composition and perturbed top and bottom interfaces with preferential oxidation and diffusion of terbium. Despite of that, amorphous and homogeneous alloy film remains in a bulk-like part. The composition of that bulk-like part of the magnetic layer, labeled as effective composition, is biased when compared with the depth-integrated composition. The magnetic properties of the film are mostly dictated by this effective composition, which we show changes with different top and bottom interfaces.
66 - J. Kim 1999
We propose a di-interstitial model for the P6 center commonly observed in ion implanted silicon. The di-interstitial structure and transition paths between different defect orientations can explain the thermally activated transition of the P6 center from low-temperature C1h to room-temperature D2d symmetry. The activation energy for the defect reorientation determined by ab initio calculations is 0.5 eV in agreement with the experiment. Our di-interstitial model establishes a link between point defects and extended defects, di-interstitials providing the nuclei for the growth.
Thermally activated magnetization decay is studied in ensembles of clusters of interacting dipolar moments by applying the master-equation formalism, as a model of thermal relaxation in systems of interacting single-domain ferromagnetic particles. So lving the associated master-equation reveals a breakdown of the energy barrier picture depending on the geometrical symmetry of structures. Deviations are most pronounced for reduced symmetry and result in a strong interaction dependence of relaxation rates on the memory of system initialization. A simple two-state system description of an ensemble of clusters is developed which accounts for the observed anomalies. These results follow from a semi-analytical treatment, and are fully supported by kinetic Monte-Carlo simulations.
Perpendicularly magnetized films showing small saturation magnetization, $M_mathrm{s}$, are essential for spin-transfer-torque writing type magnetoresistive random access memories, STT-MRAMs. An intermetallic compound, {(Mn-Cr)AlGe} of the Cu$_2$Sb-t ype crystal structure was investigated, in this study, as a material showing the low $M_mathrm{s}$ ($sim 300$ kA/m) and high-perpendicular magnetic anisotropy, $K_mathrm{u}$. The layer thickness dependence of $K_mathrm{u}$ and effects of Mg-insertion layers at top and bottom (Mn-Cr)AlGe$|$MgO interfaces were studied in film samples fabricated onto thermally oxidized silicon substrates to realize high-$K_mathrm{u}$ in the thickness range of a few nanometer. Optimum Mg-insertion thicknesses were 1.4 and 3.0 nm for the bottom and the top interfaces, respectively, which were relatively thick compared to results in similar insertion effect investigations on magnetic tunnel junctions reported in previous studies. The cross-sectional transmission electron microscope images revealed that the Mg-insertion layers acted as barriers to interdiffusion of Al-atoms as well as oxidization from the MgO layers. The values of $K_mathrm{u}$ were about $7 times 10^5$ and $2 times 10^5$ J/m$^3$ at room temperature for 5 and 3 nm-thick (Mn-Cr)AlGe films, respectively, with the optimum Mg-insertion thicknesses. The $K_mathrm{u}$ at a few nanometer thicknesses is comparable or higher than those reported in perpendicularly magnetized CoFeB films which are conventionally used in MRAMs, while the $M_mathrm{s}$ value is one third or less smaller than those of the CoFeB films. The developed (Mn-Cr)AlGe films are promising from the viewpoint of not only the magnetic properties, but also the compatibility to the silicon process in the film fabrication.
التعليقات
جاري جلب التعليقات جاري جلب التعليقات
سجل دخول لتتمكن من متابعة معايير البحث التي قمت باختيارها
mircosoft-partner

هل ترغب بارسال اشعارات عن اخر التحديثات في شمرا-اكاديميا