Spin–orbit torque in perpendicularly magnetized[Pt/Ni]multilayers

The performance of spin–orbit torque(SOT)in heavy metal/ferromagnetic metal periodic multilayers has attracted widespread attention.In this paper,we have successfully fabricated a series of perpendicular magnetized[Pt(2-t)/Ni(t)]_4 multilayers,and studied the SOT in the multilayers by varying the thickness of Ni layer t.The current induced magnetization switching was achieved with a critical current density of 1×10^(7)A/cm^(2).The damping-like SOT efficiencyξ_(DL)was extracted from an extended harmonic Hall measurement.We demonstrated that theξ_(DL)can be effectively modulated by t_(Pt)/t_(Ni)ratio of Pt and Ni in the multilayers.The SOT investigation about the[Pt/Ni]N multilayers might provide new material candidates for practical perpendicular SOT-MRAM devices.

Recent progress in perpendicularly magnetized Mn-based binary alloy films

In this article, we review the recent progress in growth, structural characterizations, magnetic properties, and related spintronic devices of tetragonal MnxGa and MnxA1 thin films with perpendicular magnetic anisotropy. First, we present a brief introduction to the demands for perpendicularly magnetized materials in spintronics, magnetic recording, and perma- nent magnets applications, and the most promising candidates of tetragonal MnxGa and MnxA1 with strong perpendicular magnetic anisotropy. Then, we focus on the recent progress of perpendicularly magnetized MnxGa and MnxA1 respec- tively, including their lattice structures, bulk synthesis, epitaxial growth, structural characterizations, magnetic and other spin-dependent properties, and spintronic devices like magnetic tunneling junctions, spin valves, and spin injectors into semiconductors. Finally, we give a summary and a perspective of these perpendicularly magnetized Mn-based binary alloy films for future applications.

Perpendicularly assembled oriented electrospinning nanofibers based piezoresistive pressure sensor with wide measurement range

With the rapid development of wearable electronics,flexible pressure sensors have attracted wide attention in human–computer interaction and intelligent machines.However,it is a challenge to achieve a sensor with high sensitivity,wide measurement range,and wearing comfortability.Here,we develop an oriented electrospinning thermoplastic polyurethane/polyacrylonitrile(TPU/PAN)nanofibers(OETPN)based piezoresistive pressure sensor(PONPS)in which the active layer and the electrode are assembled perpendicularly.The interdigital electrode is fabricated by spraying silver nanowires(AgNWs)on the OETPN through a mask plate.The active layer is composed of OETPN coated with MXene,encapsulated on the electrode by polyurethane(PU)film.The porous structure of nanofibers membrane broadens the measurement range of the sensor.Employing oriented nanofibers as active layer can improve the sensitivity in low pressure,because oriented nanofibers without interweaving nanofibers are more compressible than disordered nanofibers.Electrode prepared using the spraying method creates nanoscale microstructure and increases sensitivity.The perpendicular assembly has greater response between the active layer and the electrode than the parallel assembly to improve the sensitivity.The sensor exhibits high sensitivity(6.71 kPa^(−1),0.02–2 kPa)and wide measurement range(0.02–700 kPa).The sensor can detect weak signals such as radial artery.A pressure array constructed precisely represents the distribution of pressure.An intelligent throat is created by combining machine learning algorithms with the PONPS.It can detect and recognize subtle throat vibrations while speaking,achieving recognition accuracy up to 100%using support vector machine(SVM)for five words with different syllables.The fabricated sensor shows promising prospects in personal healthcare and intelligent robots.

页岩气开采中的压力变化与气液传质规律

根据页岩气的赋存及流动机理,建立考虑页岩渗吸与吸附、渗流与扩散的流动方程,采用线段源叠加解等效为压裂产生的压力分布作为方程的初始条件,使用非结构PEBI(perpendicular bisection)网格对水平井多段压裂井进行网格划分,有限体积法进行离散。利用高频压力监测的闷井压力数据验证了算法程序的可靠性。研究得出以下结果:(1)发现页岩气开发的压力双漏斗及气液双向传质流动规律;(2)依据这一规律给出页岩气压最佳闷井时间和最优排采制度。

Perpendicular-Cutdepth:Perpendicular Direction Depth Cutting Data Augmentation Method

Depth estimation is an important task in computer vision.Collecting data at scale for monocular depth estimation is challenging,as this task requires simultaneously capturing RGB images and depth information.Therefore,data augmentation is crucial for this task.Existing data augmentationmethods often employ pixel-wise transformations,whichmay inadvertently disrupt edge features.In this paper,we propose a data augmentationmethod formonocular depth estimation,which we refer to as the Perpendicular-Cutdepth method.This method involves cutting realworld depth maps along perpendicular directions and pasting them onto input images,thereby diversifying the data without compromising edge features.To validate the effectiveness of the algorithm,we compared it with existing convolutional neural network(CNN)against the current mainstream data augmentation algorithms.Additionally,to verify the algorithm’s applicability to Transformer networks,we designed an encoder-decoder network structure based on Transformer to assess the generalization of our proposed algorithm.Experimental results demonstrate that,in the field of monocular depth estimation,our proposed method,Perpendicular-Cutdepth,outperforms traditional data augmentationmethods.On the indoor dataset NYU,our method increases accuracy from0.900 to 0.907 and reduces the error rate from0.357 to 0.351.On the outdoor dataset KITTI,our method improves accuracy from 0.9638 to 0.9642 and decreases the error rate from 0.060 to 0.0598.

Perpendicularly Self-Oriented and Shape-Controlled L10-FePt Nanorods Directly Synthesized by a Temperature-Modulated Process

The synthesis and self-assembly of tetragonal phase-containing L10-Fe55Pt45 nanorods with high coercive field is described. The experimental procedure resulted in a tetragonal/cubic phase ratio close to 1：1 for the as-synthesized nanoparticles. Using different surfactant/solvent proportions in the process allowed control of particle morphology from nanospheres to nanowires. Monodisperse nanorods with lengths of 60 ＋ 5 nm and diameters of 2-3 nm were self-assembled in a perpendicular oriented array onto a substrate surface using hexadecylamine as organic spacer. Magnetic alignment and properties assigned, respectively, to the shape anisotropy and the tetragonal phase suggest that the self-assembled materials are a strong candidate to solve the problem of random magnetic alignment observed in FePt nanospheres leading to applications in ultrahigh magnetic recording （UHMR） systems capable of achieving a performance of the order of terabits/in2.

Research on perpendicularly magnetized electrolessly plated cobalt alloy films using MFM

Many methods have been used to prepare the high-density perpendicular magnetic recording media. One of them is the electroless plating method. To study its potency for magnetic recording, the film’s magnetic structure is to be known. Magnetic force microscope (MFM) is a kind of scanning probe microscope (SPM). By controlling the scanning of a magnetized tip along the surface of the sample, MFM can image the magnetic field near the surface. MFM is widely used in studying magnetic head and magnetic structure of digits on disks, such as the size and shape of the digits, the recording noise of the media, the performance of rewriting and the capability to record

High-yield fabrication of perpendicularly magnetised synthetic antiferromagnetic nanodiscs

Synthetic antiferromagnetic (SAF) particles with perpendicular anisotropy display a number of desirable characteristics for applications in biological and other fluid environments. We present an efficient and effective method for the patterning of ultrathin Ruderman-Kittel-Kasuya-Yoshida coupled, perpendicularly magnetised SAFs using a combination of nanosphere lithography and ion milling. A Ge sacrificial layer is utilised, which provides a clean and simple lift-off process, as well as maintaining the key magnetic properties that are beneficial to target applications. We demonstrate that the method is capable of producing a particularly high yield of well-defined, thin film based nanoparticles.

Mo-based perpendicularly magnetized thin films with low damping for fast and low-power consumption magnetic memory

Perpendicular magnetic anisotropy-based magnetic tunnel junctions(p-MTJs) with low Gilbert damping constant(α) are of particular interest for fast and low-power consumption magnetic random-access memory(MRAM). However, obtaining a faster switching speed and lower power consumption is still a big challenge. Herein, we report a Mo-based perpendicular double free layer structure with a low Gilbert damping constant of 0.02 relative to W-based films, as measured by time-resolved magnetooptical Kerr effect equipment. To show the influence of different film structures on the Gilbert damping constant, we measured the Mo-based single free layer. Thereafter, we deposited the full stacks with the Mo-based double free layer and obtained a high tunneling magnetoresistance of 136.3% and high thermal stability. The results of high-resolution transmission electron microscopy(HR-TEM) and energy-dispersive X-ray spectroscopy(EDS) showed that the Mo-based films had better crystallinity,sharper interfaces, and weaker diffusion than the W-based films and thus produced a weaker external contribution of the Gilbert damping constant. As a result of the weak spin-orbit coupling in the Mo-based structure, the intrinsic contribution of the Gilbert damping constant was also weak, thereby leading to the small Gilbert damping constant of the Mo-based stacks. In addition, the macro-spin simulation results demonstrated that the magnetization switching by the spin transfer torque of the Mo-based MTJs was faster than that of the W-based MTJs. These findings help to understand the mechanism behind the good performance of Mo-based p-MTJ films and show the great promise of these structures in low-power consumption MRAM or other spintronic devices.

Thickness-dependent magnetic properties in Pt/[Co/Ni]_(n) multilayers with perpendicular magnetic anisotropy

We systematically investigated the Ni and Co thickness-dependent perpendicular magnetic anisotropy(PMA)coefficient,magnetic domain structures,and magnetization dynamics of Pt(5 nm)/[Co(t_(Co))/Ni(t_(Ni))]_(5)/Pt(1 nm)multilayers by combining the four standard magnetic characterization techniques.The magnetic-related hysteresis loops obtained from the field-dependent magnetization M and anomalous Hall resistivity(AHR)ρxy showed that the two serial multilayers with t_(Co)=0.2 nm and 0.3 nm have the optimum PMA coefficient K_(U) as well as the highest coercivity H_(C) at the Ni thickness t_(Ni)=0.6 nm.Additionally,the magnetic domain structures obtained by magneto-optic Kerr effect(MOKE)microscopy also significantly depend on the thickness and K_(U) of the films.Furthermore,the thickness-dependent linewidth of ferromagnetic resonance is inversely proportional to K_(U) and H_(C),indicating that inhomogeneous magnetic properties dominate the linewidth.However,the intrinsic Gilbert damping constant determined by a linear fitting of the frequency-dependent linewidth does not depend on the Ni thickness and K_(U).Our results could help promote the PMA[Co/Ni]multilayer applications in various spintronic and spin-orbitronic devices.

Investigation of magnetization reversal and domain structures in perpendicular synthetic antiferromagnets by first-order reversal curves and magneto-optical Kerr effect

Perpendicular synthetic-antiferromagnet(p-SAF) has broad applications in spin-transfer-torque magnetic random access memory and magnetic sensors. In this study, the p-SAF films consisting of (Co/Ni)3]/Ir(tIr)/[(Ni/Co)3are fabricated by magnetron sputtering technology. We study the domain structure and switching field distribution in p-SAF by changing the thickness of the infrared space layer. The strongest exchange coupling field(Hex) is observed when the thickness of Ir layer(tIr) is 0.7 nm and becoming weak according to the Ruderman–Kittel–Kasuya–Yosida-type coupling at 1.05 nm,2.1 nm, 4.55 nm, and 4.9 nm in sequence. Furthermore, the domain switching process between the upper Co/Ni stack and the bottom Co/Ni stack is different because of the antiferromagnet coupling. Compared with ferromagnet coupling films, the antiferromagnet samples possess three irreversible reversal regions in the first-order reversal curve distribution.With tIrincreasing, these irreversible reversal regions become denser and smaller. The results from this study will help us understand the details of the magnetization reversal process in the p-SAF.

Electric-field control of perpendicular magnetic anisotropy by resistive switching via electrochemical metallization

Electric-field control of perpendicular magnetic anisotropy(PMA) is a feasible way to manipulate perpendicular magnetization,which is of great importance for realizing energy-efficient spintronics.Here,we propose a novel approach to accomplish this task at room temperature by resistive switching(RS) via electrochemical metallization(ECM) in a device with the stack of Si/SiO_(2)/Ta/Pt/Ag/Mn-doped ZnO(MZO)/Pt/Co/Pt/ITO.By applying certain voltages,the device could be set at high-resistance-state(HRS) and low-resistance-state(LRS),accompanied with a larger and a smaller coercivity(H_(C)),respectively,which demonstrates a nonvolatile E-field control of PMA.Based on our previous studies and the present control experiments,the electric modulation of PMA can be briefly explained as follows.At LRS,the Ag conductive filaments form and pass through the entire MZO layer and finally reach the Pt/Co/Pt sandwich,leading to weakening of PMA and reduction of H_(C).In contrast,at HRS,most of the Ag filaments dissolve and leave away from the Pt/Co/Pt sandwich,causing partial recovery of PMA and an increase of H_(C).This work provides a new clue to designing low-power spintronic devices based on PMA films.

High repetition granular Co/Pt multilayers with improved perpendicular remanent magnetization for high-density magnetic recording

Thanks to the strong perpendicular magnetic anisotropy(PMA), excellent processing compatibility as well as novel spintronic phenomenon, Co/Pt multilayers have been attracting massive attention and widely used in magnetic storage.However, reversed magnetic domains come into being with the increasing layer repetition ‘N’ to reduce magneto-static energy, resulting in the remarkable diminishment of the remanent magnetization(Mr). As a result, the product of Mrand thickness(i.e., the remanent moment-thickness product, Mrt), a key parameter in magnetic recording for reliable data storing and reading, also decreases dramatically. To overcome this issue, we deposit an ultra-thick granular [Co/Pt]80multilayer with a total thickness of 68 nm on granular SiNxbuffer layer. The Mrt value, Mrto saturation magnetization(Ms) ratio as well as out of plane(OOP) coercivity(Hcoop) are high up to 2.97 memu/cm^(2), 67%, and 1940 Oe(1 Oe = 79.5775 A·m^(-1)),respectively, which is remarkably improved compared with that of continuous [Co/Pt]80multilayers. That is because large amounts of grain boundaries in the granular multilayers can efficiently impede the propagation and expansion of reversed magnetic domains, which is verified by experimental investigations and micromagnetic simulation results. The simulation results also indicate that the value of Mrt, Mr/Msratio, and Hcoopcan be further improved through optimizing the granule size, which can be experimentally realized by manipulating the process parameter of SiNxbuffer layer. This work provides an alternative solution for achieving high Mrt value in ultra-thick Co/Pt multilayers, which is of unneglectable potential in applications of high-density magnetic recording.

Comparison of methods for turbulence Doppler frequency shift calculation in Doppler reflectometer

The Doppler reflectometer(DR),a powerful diagnostic for the plasma perpendicular velocity(u⊥)and turbulence measurement,has been widely used in various fusion devices.Many efforts have been put into extracting the Doppler shift from the DR signal.There are several commonly used methods for Doppler shift extraction,such as the phase derivative,the center of gravity,and symmetric fitting(SFIT).However,the strong zero-order reflection component around 0 kHz may interfere with the calculation of the Doppler shift.To avoid the influence of the zerofrequency peak,the asymmetric fitting(AFIT)method was designed to calculate the Doppler shift.Nevertheless,the AFIT method may lead to an unacceptable error when the Doppler shift is relatively small compared to the half width at half maximum(HWHM).Therefore,an improved method,which can remove the zero-frequency peak and fit the remaining Doppler peak with a Gaussian function,is devised to extract the Doppler shift.This method can still work reliably whether the HWHM is larger than the Doppler shift or not.

On the Physical Nature of Einstein’s Gravitational Lensing Effect

Gravitational lensing has become a powerful research tool for exploring the distribution of matter and energy in the universe nowadays, as glare phenomena around the Sun and massive galaxies are indeed observed on the Earth. What is the physical nature of gravitational lensing effect? Both Newton’s law of gravitation and Einstein’s theory of relativity are difficult to physically explain these glare phenomena. This study points out that the observed glare around the Sun and large galaxies is a result or product of the orthogonal interaction of high-energy particles emitted from different star light sources. It shows a new physical state associated with abnormal high mass-energy density.

Application of CPD in Analyzing EM Field in Stratified Media with an Uniform Plane Wave Slanted Through

The Counter-Propagation Deduction (CPD) method suggested by the authors is a new one for analyzing electromagnetic (EM) field in stratified media. The mechanism or the method is briefly introduced, and the rield in a layered medium in the presence or slant incidence of a perpendicularly or parallelly polarized electric wave is investigated. Some illustrative examples show that the method is capable of providing the direct mathematic expressions of the fields in an arbitrary layer, and is convenient for numerical evaluation through an unified program, irrespective of the number of medium layers.

带蒂鼻底黏膜瓣联合自体筛骨垂直板修补鼻中隔穿孔的临床观察

目的 回顾性分析带蒂鼻底黏膜瓣联合自体筛骨垂直板修补鼻中隔穿孔的疗效。方法 19例鼻中隔穿孔患者均采用鼻内镜下带蒂鼻底黏膜瓣联合筛骨垂直板修补鼻中隔穿孔,并采用纳吸棉对术后创面行填塞止血。结果19例行鼻中隔穿孔修补的患者术后随访1~3个月,17例(89.47%)患者鼻中隔黏膜均愈合良好,穿孔均修补成功,且形态恢复良好,2例(10.52%)患者因术后未能按时随访,未能观察疗效。结论 采用带蒂鼻底黏膜瓣联合自体筛骨垂直板修补鼻中隔穿孔,自体组织取材方便,经济实惠,无排异反应,带蒂鼻底黏膜瓣血供好,修补成活率高,疗效可靠。

Mechanical Properties and Stress Strain Relationship Models for Bamboo Scrimber

In order to investigate the basic mechanical properties and stress strain relationship model for bamboo scrimber manufactured based on a new technique,a large quantities of experiments have been carried out.Based on the analysis of the test results,the following conclusions can be drawn.Two main typical failure modes were classified for bamboo scrimber specimens both under tension parallel to grain and tension perpendicular to grain.Brittle failure happened for all tensile tests.The slope values for the elastic stages have bigger discreteness compared with those for the specimens under tensile parallel to grain.The failure modes for bamboo scrimber specimens under compression parallel to grain could be divided into four.Only one main failure mode happened both for the bending specimens and the shear specimens.With the COV values of 28.64 and 25.72 respectively,the values for the strength and elastic modulus under tensile perpendicular to grain have the largest discreteness for bamboo scrimber.From the point of CHV values,the relationship among the mechanical parameters for bamboo scrimber were proposed based on the test results.Compared with other green building materials,bamboo scrimber manufactured based on a new technique has better mechanical performance and could be used in construction area.Three stress strain relationship models which are four-linear model,quadratic function model,and cubic function model were proposed for bamboo scrimber specimens manufactured based on a new technique.The latter two models gives better prediction for stress strain relationship in elastic plastic stage.

Compression Behaviors of Parallel Bamboo Strand Lumber Under Static Loading

In order to investigate the influence of length and compression directions upon behaviour of parallel bamboo strand lumber(PBSL)specimens,240 axial compression tests have been performed.With three similar one different typical failure modes,the mechanical performance for PBSL specimens under compression parallel to grain and perpendicular to grain are different as a whole.From the point of the characteristic values,the compression strength parallel to grain is 2.1 times of the compression strength perpendicular to grain.The elastic modulus for compression parallel to grain is 3.64 times of the compression strength perpendicular to grain.While the compression ratios along two compression directions are equal to each other.The bigger Poisson ratios for one typical side surface is 3.93 times of that for another typical side surface for PBSL specimens under compression perpendicular to grain,and the bigger value is equal to that for PBSL specimens under compression parallel to grain.Length can influence the mechanical properties of the PBSL specimens.The size 50 mm×50 mm×100 mm should be good choice for the standard or code to measure the compression strength.PBSL materials have better ductility under compression parallel to grain than that under compression perpendicular to grain.Stress-strain relationship models were proposed for PBSL specimens under compression parallel to grain and perpendicular to grain,respectively.These proposed models gave a good agreement with the test results.

Electron-Induced Perpendicular Graphene Sheets Embedded Porous Carbon Film for Flexible Touch Sensors

Graphene-based materials on wearable electronics and bendable displays have received considerable attention for the mechanical flexibility,superior electrical conductivity,and high surface area,which are proved to be one of the most promising candidates of stretching and wearable sensors.However,polarized electric charges need to overcome the barrier of graphene sheets to cross over flakes to penetrate into the electrode,as the graphene planes are usually parallel to the electrode surface.By introducing electron-induced perpendicular graphene(EIPG)electrodes incorporated with a stretchable dielectric layer,a flexible and stretchable touch sensor with"in-sheet-chargestransportation"is developed to lower the resistance of carrier movement.The electrode was fabricated with porous nanostructured architecture design to enable wider variety of dielectric constants of only 50-μm-thick Ecoflex layer,leading to fast response time of only 66 ms,as well as high sensitivities of 0.13 kPa-1 below 0.1 kPa and 4.41 MPa-1 above 10 kPa,respectively.Moreover,the capacitance-decrease phenomenon of capacitive sensor is explored to exhibit an object recognition function in one pixel without any other integrated sensor.This not only suggests promising applications of the EIPG electrode in flexible touch sensors but also provides a strategy for internet of things security functions.