Modeling the processes of atom structure formation of a superconducting spin valve

The paper considers the modeling of a multilayer nanocomposite, the combination of elements of which gives rise to a spin valve effect. The relevance and importance of effects in the field of spintronics and related materials and devices are described. We study the composition and atomic structure of individual layers of a multilayer nanocomposite, as well as the composition and morphology of the interface of nanocomposite layers. We analyzed a sample with a periodic superconductor-ferromagnet structure consisting of more than 20 alternating layers of niobium and cobalt. The deposition process took place in a deep vacuum. The simulation was carried out by the molecular dynamics method using the potential of the modified immersed atom method. The formation of layers was carried out in a stationary mode. The temperature was adjusted using the Nose-Hoover thermostat. The deposition of each nanofilm ended with a relaxation stage for the necessary stabilization and restructuring of the formed nanocomposite. Three deposition temperature regimes were considered: 300 K, 500 K, and 800 K. For these modes, we analysed the atomic structure of nanofilms and transition regions (interface) formed between the layers. A study of the atomic structure of nanofilms showed that niobium is formed by crystalline regions of different orientations. A cobalt nanofilm is characterized by a structure close to amorphous. The structural features of the interface between the superconductor-ferromagnet layers largely depend on a relief of the surface onto which the deposition is made. The smallest variation in atomic composition is observed in the first niobium-cobalt contact zone, since the formation of the first nanofilm occurs on an even plane of the substrate. An analysis of the influence of the temperature regime during the formation of the nanosystem shows the dependence of the processes of formation of multilayer nanofilm formation, the interface of nanolayers, as well as the composition and morphology of heterostructures on the temperature at which a nanocomposite is manufactured. An increased temperature leads to the formation of a more rarefied structure of nanolayers and an increase in the zones of the interface of nanolayers due to the diffusion of atoms of the sprayed materials.

Response of near-inertial energy to a supercritical tropical cyclone and jet in the South China Sea: modelling study

We used a well-validated three-dimensional ocean model to investigate the process of energetic response of near-inertial oscillations (NIOs) to a tropical cyclone (TC) and strong background jet in the South China Sea (SCS). We found that the NIO and near-inertial kinetic energy (KEni) varied distinctly during different stages of the TC forcing, and the horizontal and vertical transport of KEni was largely modulated by the velocity and vorticity of the jet. The KEni reached its peak value within ∼1/2 the inertial period after the initial TC forcing stage in the upper layer, decayed quickly by 1∕2 in the next 2 d, and further decreased at a slower rate during the relaxation stage of the TC forcing. Analyses of the KEni balance indicate that the weakened KEni in the upper layer during the forcing stage was mainly attributed to the downward KEni transport due to pressure work through the vertical displacement of isopycnal surfaces, while upward KEni advection from depths also contributed to the weakening in the TC-induced upwelling region. In contrast, during the relaxation stage as the TC moved away, the effect of vertical advection on KEni reduction was negligible and the KEni was chiefly removed by the outward propagation of inertial-gravity waves, horizontal advection, and viscous dissipation. Both the outward wave propagation and horizontal advection by the jet provided the KEni source in the far field. During both stages, the negative geostrophic vorticity south of the jet facilitated the vertical propagation of inertial-gravity waves.

Response of near-inertial energy to a supercritical tropical cyclone and jet stream in the South China Sea: modeling study

We used a well-validated three-dimensional ocean model to investigate the process of energetic response of near-inertial oscillations (NIOs) to a tropical cyclone (TC) and strong background jet stream in the South China Sea (SCS). We found that the NIO and near-inertial kinetic energy (KEni) varied distinctly during different stages of the TC forcing, and the horizontal and vertical transport of KEni was largely modulated by the velocity and vorticity of the jet stream. The KEni reached its peak value within ~one-half the inertial period after the initial TC forcing stage in the upper layer, decayed quickly by one-half in the next two days, and further decreased in a slower rate during the relaxation stage of the TC forcing. Analyses of the KEni balance indicate that the weakened KEni in the upper layer during the forcing stage was mainly attributed to the downward KEni transport due to pressure work through the vertical displacement of isopycnal surface, while the upward KEni advection from depths also contributed to the weakening in the TC-induced upwelling region. In contrast, during the relaxation stage as TC moved away, the effect of vertical advection on KEni reduction was negligible and the KEni was chiefly removed by the outward propagation of inertial-gravity waves, horizontal advection and viscous dissipation. Both the outward wave propagation and horizontal advection by the jet stream provided the KEni source in the far-field. During both stages, the negative geostrophic vorticity south of the jet stream facilitated the vertical propagation of inertial-gravity waves.

Adsorption dynamics of tannin on deacetylated electrospun Konjac glucomannan fabric

We demonstrate the adsorption dynamics of Konjac glucomannan electrospun nanofabrics consisting of an initial diffusion-limited stage and a late stoichiometric relaxation stage and show how to design efficient adsorption using the crossover time.

Interaction between the Dislocations and Precipitates in Fe-40Ni Alloy during Stress Relaxation

Transmission electron microscopy (TEM) was used to study the interaction between the dislocations and strain induced precipitates during relaxation process after deformation in Fe-40Ni alloy. The experimental results demonstrate that the dislocation density is very high and distribute randomly before relaxation. As the relaxation time increasing, dislocation walls will form gradually by polygonization. The strain induced precipitates retards their progress. In the final relaxation stage, most dislocations get rid of pinning of precipitates and the dislocation walls have developed into subgrains with large size.