A dual-stage analytical model for FRPs drilling considering step structure

It is a matter of debate whether a pillar or a stepped structure better retains magnetic tunnel junctions’ (MTJs) performance while scaling down. In this work we use micromagnetic simulation to model the scaling effects on the free-layer’s stray-field (Hstray) for the two MTJ structures. The model was built on an MTJ containing a synthetic ferromagnetic (SyF) layer (free-layer/MgO/reference-layer) and a synthetic antiferromagnetic (SyAF) layer (reference-layer/Ru/hard-layer). Approximate Hstray strength is obtained in both structures with a free-layer of ~ 100nm. However, upon size reduction the Hstray raises significantly in the pillar structure, but it appears less responsive in the stepped structure. This trend is shared by experimental results with the MTJ reduced from 130 to 80 nm. We are suggested that the stepped structure is a more promising candidate on mitigating Hstray in pursuit of high density MRAM [1]. The combined effects of Hstray and Dzyaloshinskii–Moriya interaction (DMI) on switching current density (Jc) were also calculated for a 30 nm free-layer MTJ. The in-plane Hstray appears to interact with the DMI in a complementary or a competing manner, depending on the sign of the DMI and initial switching state (parallel or antiparallel) of the MTJ. The stepped structure is able to reduce Jc more effectively than the pillar case. This is due to strong mediation from the Ruderman-Kittel-Kasuya-Yosida (RKKY) interaction of the SyAF layer in the stepped structure.

Ni/NiO/Cr MIM diodes with various structures namely, stacked, stepped self aligned, stepped manual aligned and stepped spacer, were fabricated. Their dc electrical responses were analyzed to identify the effects of diode design on asymmetry and emission current. It was found that the stepped structure with an oxide spacer prevented shorting at the step thus circumventing premature breakdown as exhibited by the other structures. These structures demonstrated better asymmetry and a high enough emission current alleviating the issues caused by the other structures. It was also observed that the current density of the self aligned stepped structure showed less variance across devices than the stepped spacer structure. On the other hand, the resistance of the same structure showed to be more ohmic in nature when compared to the stepped structure with spacer.

Recent oceanographic observations in the Tyrrhenian Sea and Sardinian Channel show a well-defined stepped thermohaline structure below the core of the Levantine water (∼500 m). Such a stepped structure has also been found under the Mediterranean outflow west of Gibraltar. The effects of the Tyrrhenian Sea stepped structure on sound propagation are examined qualitatively using ray tracing techniques. The predominant effect occurs for energy that has travelled along rays that have vertexed in the steps. Shadow zones, regions of high propagation loss, and caustics are then generated.

Scanning-tunneling-microscopy studies of [1\ifmmode\bar\else\textasciimacron\fi{}12] and [11\ifmmode\bar\else\textasciimacron\fi{}0] step structures on cleaved GaAs(110) show that [1\ifmmode\bar\else\textasciimacron\fi{}12] steps are straight whereas [11\ifmmode\bar\else\textasciimacron\fi{}0] steps are made up of kinks along [1\ifmmode\bar\else\textasciimacron\fi{}12]. These step and kink structures are very different from those on Si surfaces. Through quantitative analysis of terrace-width and kink-length distributions, we show that [11\ifmmode\bar\else\textasciimacron\fi{}0] steps are weakly interacting while kinks are noninteracting.

The exact exchange-correlation (xc) potential of time-dependent density functional theory has been shown to have striking features. For example, step and peak features are generically found when the system is far from its ground-state, and these depend nonlocally on the density in space and time. We analyze the xc potential by decomposing it into kinetic and interaction components and comparing each with their exact-adiabatic counterparts, for a range of dynamical situations in model one-dimensional two-electron systems. We find that often, but not always, the kinetic contribution is largely responsible for these features that are missed by the adiabatic approximation. The adiabatic approximation often makes a smaller error for the interaction component, which we write in two parts, one being the Coulomb potential due to the time-dependent xc hole. Non-adiabatic features of the kinetic component were also larger than those of the interaction component in cases that we studied when there is negligible step structure. In ground-state situations, step and peak structures arise in cases of static correlation, when more than one determinant is essential to describe the interacting state. We investigate the time-dependent natural orbital occupation numbers and find the corresponding relation between these and the dynamical step is more complex than for the ground-state case.

Mathematical model of stepped rotor type 12/14 bearingless switched reluctance motor based on maxwell stress method

Currently, many researches have developed several strategies to design the surface structures of hydroxyapatite (HA), and have proved that the surface structures are pivotal in guiding the adhesion of bone marrow mesenchymal stem cells (BMSCs) as well as subsequent cellular behaviours. Most of these strategies, such as altering roughness and constructing surface patterning of HA, involve the construction of geometric topographies at the micro/nanoscale. However, besides geometric topographies, crystal defects are also important characteristics of surface structures and would alter many local physicochemical properties, which is critical for contact between cells and bioceramic surfaces. For the practical applications of crystal defects, a major hindrance is that crystal defects are usually unstable and easily eliminated during crystallization, which limits the large-scale fabrication of materials with crystal defects. In this work, given that stepped structures contain massive stable crystal defects on their step edges and kinks, we proposed a feasible and efficient method to fabricate HA dishes with stepped structures on their surfaces. First, plate-like HA mesocrystals were prepared from CaHPO4via topotactic transformation, and were shaped into HA dishes by vacuum-filtration. Then, a sintering process was applied to facilitate the formation of stepped structures on the surfaces. We demonstrated that the generation of stepped structures could restrict the adhesion of BMSCs and showed the restriction effect is highly correlated with the density of exposed stepped structures. This phenomenon is interesting and the construction of a cell adhesion model is robust and easy, the underlying mechanisms of which deserve further exploration. Furthermore, constructing stepped structures on surfaces may be a new useful strategy to regulate cell adhesion and could also cooperate with other methods that do not need change in the surface crystal structure.

This paper reports the fabrication of InN layers on the epitaxial graphene (EG) using radio-frequency plasma-assisted molecular beam epitaxy (RF-MBE). Prior to the fabrication of InN, single crystalline EG with step and terrace structure was formed on 6H-SiC (0001) substrate in an Ar ambient by the Si sublimation method. Single crystalline epitaxial layers of InN with smooth surfaces are successfully fabricated on the EG using RF-MBE. InN layers with terrace and step structure are grown on the graphene surface up to 2MLs, and InN are grown in a layer by layer 2D growth mode. If the number of layers is increased above 3 MLs, the terrace and steps disappear, and the growth mode changes to 3D mode. The Raman spectroscopy analysis shows that the interfacial stress is reduced for the InN layer grown on the EG surface. The quality of the grown InN layer on the EG surface achieved at present is comparable to the InN film grown on sapphire. This work opens the possibility of growing high-quality InN layers on the EG surface in the near future.

On the basis of the discrete element method (DEM), the non-linear mechanical model of the wear-resistant body surfaces was established. The step, convexity, and scale arranged structures of the wear-resistant surfaces and their abrasive wear systems were established with the software PFC2D®. Through the qualitative analysis on the morphology, the contact-bond fields and the contact-force chains, the minor injuries and the breakaway of the debris of the wear behaviors are observed. Besides, the dynamic force acted on the wear-resistant structures was studied through the quantitative analysis. Numeral simulation shows that the step structure was worn dramatically in its tip part, the convexity structure distributes the stress prominently and the scale structure shows the best wear-resistant function. The wear loss of the front monomers of the step, convexity, and scale structures are 2.43%, 2.02%, and 1.12% respectively after being worn for eight minutes in the simulation, which are in accordance with the experimental results. The numerical simulation on the abrasive wear behavior of the biological wear-resistant structures by DEM helps to reveal the wearable mechanism of the wear-resistant surfaces. Moreover, it provides a new method for studying the bionic wear-resistant surfaces and structures.

The principal reconstructions found on the low-index planes of GaAs and ZnSe can be explained in terms of a simple electron counting model. A surface structure satisfies this model if it is possible to have all the dangling bonds on the electropositive element (Ga or Zn) empty and the dangling bonds on the electronegative element (As or Se) full, given the number of available electrons. This condition will necessarily result in there being no net surface charge. The justification for this model is discussed. The GaAs(001)-(2\ifmmode\times\else\texttimes\fi{}4) reconstruction is known to involve surface dimers. It is shown that a (2\ifmmode\times\else\texttimes\fi{}4) unit cell with three dimers and one dimer vacancy is the smallest unit cell that satisfies the electron counting model for this surface. The electron counting model is used to explain the structure of islands imaged by scanning tunneling microscopy on the GaAs(001)-(2\ifmmode\times\else\texttimes\fi{}4) surface. The model shows that island structures built up from complete (2\ifmmode\times\else\texttimes\fi{}4) unit cells can be stable if they extend in the 2\ifmmode\times\else\texttimes\fi{} direction, but not if they extend in the 4\ifmmode\times\else\texttimes\fi{} direction. These island structures can also provide an explanation for the different step structures seen on GaAs(001) vicinal surfaces. Much less is known experimentally about step and island structures on ZnSe(001). Structures on this surface predicted by the electron counting model differ significantly from those found on GaAs(001).

The article presents the results of studying the reflection of an intense acoustic beam from stepped structures. The case of high Reynolds numbers is considered, when a sawtooth wave profile formed in the incident beam, and an obstacle in the form of a step was located normal to the acoustic axis and behind the discontinuity coordinate. When reflected from the obstacle, the acoustic beam incident on it splits into two parts, between which there is a path difference, specified by the stepped structure itself. The experiment focused on obstacles that create a path difference between the two parts of the beam during reflection, equal to 0, λ/3, λ/2, λ, etc. A broadband membrane hydrophone was used to record the shape of the profile of nonlinear waves of the incident and reflected acoustic beams at an arbitrary spatial point. This made it possible to analyze the evolution of the beam shape with increasing distance from the obstacle, as well as to study its transverse structure. The effect of doubling the characteristic frequency of a signal as an acoustic beam is reflected from a stepped structure is shown, which creates a path difference of λ/2 between the two parts of the reflected beam. It is demonstrated that the dynamics of nonlinear effects in intense beams reflected from stepped structures is similar to the transformation of the profile of acoustic waves generated by dual-frequency pump signals.

Predicted structures and stabilities of the surface A grooves and double bilayer height steps on the GaAs(001)-2 × 4 surface

We propose an aperture coupling E-bend with step structure as a robust post-wall waveguide interface to an external standard waveguide in which the posts are separated from the aperture. A 61.25 GHz model transformer gives 11.4% bandwidth for the reflection below -25 dB by using a 1.2 mm-height dielectric substrate. We have compared the mechanical tolerances of both the conventional straight structure and the proposed step structure. The step structure is more robust against mechanical errors than the conventional one. Another advantage is that the accuracy of the analysis model for the post-wall to metal-wall replacement is enhanced for the step structure.

Fracture step structure: geometrical characterization and effects on fluid flow and breakthrough curve

Isoelectronic surfactant-induced surface step structure and correlation with ordering in GaInP