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Suppression of the stimulated Raman scattering (SRS) by a stochastic phase low-coherence laser (SPLL) in homogeneous plasma is investigated by theoretical analysis and one-dimensional particle-in-cell (PIC) simulation. A simple model is established, in which the SPLL is modelled as a combination of a monochromatic laser and a broadband laser. When the phase randomness increases, the bandwidth of the SPLL is broadened and the energy proportion of the monochromatic laser component is reduced. PIC simulation shows that the SPLL can effectively suppress SRS and hot electron generation. Various phenomena in the nonlinear process, such as the nonlinear frequency shift and the competition between forward-scattering and back-scattering modes, are explained in detail.

White matter injury is the most common form of brain injury in premature infants, which is highly associated with poor brain development. White matter segmentation in brain MR images is very important for early detection of brain injury in premature infants. In this paper, a deep learning based approach is proposed to segment the white matter region of premature infants. We retrospectively analyzed 63 preterm infants with gestational age < 37 weeks who underwent MRI examination. Firstly, the U-Net deep learning neural network model is used to automatically segment white matter, U-Net++ and ResU-Net are used as controlled experimental groups, and the Dice coefficient and Iou coefficient are used as evaluation indicators for white matter segmentation. In the above experiments, the U-Net network has the best experimental results. Segmenting white matter on the training set with a Dice coefficient of 0.90 and an Iou of 0.82, respectively. The test set was used to validate the performance of the proposed model, with a Dice coefficient of 0.83 and an Iou of 0.71, respectively. Secondly, we performed image binarization step on the segmented white matter, and used Gaussian filtering, flood filling and connected component analysis to process the automatically segmented white matter region, and finally obtain a white matter region with clear boundaries.

Parallel (P) and antiparallel (AP) configurations are widely applied in magnetic heterostructures and have significant impacts on the spin-wave transmission in magnonic devices. In the present study, a theoretical investigation was conducted into the transmission of exchange-dominated spin waves with nanoscale wavelengths in a type of heterostructure including two magnetic media, of which the magnetization state can be set to the P (AP) configuration by ferromagnetic (antiferromagnetic) interfacial exchange coupling (IEC). The boundary conditions in P and AP cases were derived, by which the transmission and reflection coefficients of spin waves were analytically given and numerically calculated. In the P configuration, a critical angle $\theta_{\textrm{c}}$ always exists and has a significant influence on the transmission. Spin waves are refracted and reflected when the incident angle $\theta_{\textrm{i}}$ is smaller than the critical angle ($\theta_{\textrm{i}} < \theta_{\textrm{c}}$), while total reflection occurs as $\theta_{\textrm{i}} \geq \theta_{\textrm{c}}$. In the AP configuration, the spin-wave polarizations of medium 1 and 2 are inverse, that is, right-handed (RH) and left-handed (LH), leading to the total reflection being independent of $\theta_{\textrm{i}}$. As demonstrated by the difference in spin-wave transmission properties between the P ($\theta_{\textrm{i}} < \theta_{\textrm{c}}$) and AP cases, there is a polarization-dependent scattering. However, as $\theta_{\textrm{i}}$ exceeds $\theta_{\textrm{c}}$, the P ($\theta_{\textrm{i}} > \theta_{\textrm{c}}$) case exhibits similarities with the AP case, where the transmitted waves are found to be evanescent in medium 2 and their decay lengths are investigated.

Estimating the actual real-world effectiveness of the vaccine is an essential part of the post-marketing evaluation. This regression discontinuity design (RDD) using observational data is designed to quantify the effect of an intervention when eligibility for the intervention is based on a defined cutoff as age, making it suited to estimate vaccine effects. This approach can avoid the high cost and ethical issues; overcome difficulties in the organization and practice process in randomized controlled trials, which leads to a higher level of causal inference evidence and more realistic results. Here, we describe key features of RDD in general, and then specific scenarios, with examples, to illustrate that RDD are an essential tool for advancing our understanding of vaccine effects.疫苗保护效果的真实世界研究是其上市后评价的重要内容，采用断点回归设计进行评价，可以克服随机对照试验的伦理学、现场组织实施等困难，结果更贴近现实，并可提供较高等级的因果推断证据。本文结合实例分析，对断点回归设计的原理、方法、应用场景及未来展望进行介绍与探讨，以期为新型冠状病毒疫苗保护效果的真实世界研究提供思路。.

The dispersion relationships in antiferromagnetically coupled magnonic crystals (MCs) were investigated using micromagnetic simulations. In contrast to traditional MCs, antiferromagnetically coupled MCs have two oppositely polarized modes, enabling the realization of synthetic ferrimagnetic and synthetic antiferromagnetic MCs. The magnon flatband effect was discovered, and a large bandgap of the dispersion relation was also realized in this structure. We found that the center frequency and width of the dispersion bands with a specific polarization were influenced by the thickness and thickness ratio of the spin-up and spin-down magnetic sublattices. Based on these results, spin-wave filtering devices were proposed. Our study uncovered the magnon dispersion relations of a type of MC, which provides fresh insights into the development of ultra-efficient magnonic devices.

Background COVID-19 has had a tremendous impact on medical education. Due to concerns of the virus spreading through gatherings of health professionals, in-person conferences and rounds were largely cancelled. The purpose of this study is the evaluate the implementation of an online educational curriculum by a major Canadian orthopaedic surgery residency program in response to COVID-19. Methods A survey was distributed to residents of a major Canadian orthopaedic surgery residency program from July 10th to October 24th, 2020. The survey aimed to assess residents’ response to this change and to examine the effect that the transition has had on their participation, engagement, and overall educational experience. Results Altogether, 25 of 28 (89%) residents responded. Respondents generally felt the quality of education was superior (72%), their level of engagement improved (64%), and they were able to acquire more knowledge (68%) with the virtual format. Furthermore, 88% felt there was a greater diversity of topics, and 96% felt there was an increased variety of presenters. Overall, 76% of respondents felt that virtual seminars better met their personal learning objectives. Advantages reported were increased accessibility, greater convenience, and a wider breadth of teaching faculty. Disadvantages included that the virtual sessions felt less personal and lacked dynamic feedback to the presenter. Conclusions Results of this survey reveal generally positive attitudes of orthopaedic surgery residents about the transition to virtual learning in the setting of an ongoing pandemic. This early evaluation and feedback provides valuable guidance on how to grow this novel curriculum and bring the frontier of virtual teaching to orthopaedic education long-term.

It was recently demonstrated that introducing the shape anisotropy of a skyrmion is an alternative strategy for controlling the skyrmion Hall effect. For example, an elliptical skyrmion shows anisotropic motion under the applied driving force. Here, we study the fundamental properties of an elliptical skyrmion induced by uniaxial in-plane magnetic anisotropy. The dynamics of a skyrmion under various parameters, such as uniaxial in-plane magnetic anisotropy, interfacial Dzyaloshinskii-Moriya interaction, and the damping constant, are investigated, and we employ Thiele's theory and derive expressions for the velocity of the skyrmion that match very well with micromagnetic simulation results. We find that the skyrmion Hall angle can reach ${90}^{\ensuremath{\circ}}$ with the optimized angle between the in-plane easy axis and the current. Our results offer a potential application of racetrack memory based on skyrmions, and a type of racetrack configuration was designed.

目的 分析影响初治多发性骨髓瘤（NDMM）患者早期死亡（EM）的因素，建立其预测模型，以期识别EM风险。 方法 回顾性分析2009年5月至2017年1月吉林大学白求恩第一医院收治的275例NDMM患者，对6个月（EM6）、12个月（EM12）及24个月（EM24）内死亡患者初诊时基线特征进行单因素分析，并根据多因素分析结果建立EM的预测模型。 结果 本研究中EM6、EM12及EM24的发生率分别是5.5%、12.7%和30.2%；最常见的死亡原因为疾病复发/进展，在EM6、EM12及EM24中分别占60.0%、77.1%及84.3%。影响EM6的因素包括经白蛋白校正的血清钙（校正钙）>2.75 mmol/L和PLT75岁、国际分期系统（ISS） Ⅲ期、修订版国际分期系统（R-ISS） Ⅲ期、校正钙>2.75 mmol/L、血清肌酐>177 µmol/L、PLT75岁、PLT75岁：1分；PLT75岁、PLT

Magnon transfer torque (MTT) is regarded as capable of manipulating spin by magnons or spin waves only without spatial movement of electrons, which is a key to enrich the toolbox for magnonics. Here using a magnon current through an antiferromagnetic NiO spacer, which can be deep into a magnetic insulator ${\mathrm{Y}}_{3}{\mathrm{Fe}}_{5}{\mathrm{O}}_{12}$ (YIG), we demonstrated the perpendicular magnetization of the YIG in a YIG/NiO/Pt heterostructure could be switched. When the thickness of the magnon channel NiO was 1.5 nm, the magnon current could still maintain about $84%$ of the spin current for the YIG/Pt control device, indicating high efficiency of the NiO spacer in transferring magnon torque. Switching the perpendicular magnetization in the YIG/NiO/Pt heterostructures unambiguously verified the effect of magnon transfer torque (MTT), which may advance the development of magnonic memories and logics.

Snacking impacts the overall quality of dietary patterns, nutrition and health outcomes. Highly processed snack foods are normally unhealthy due to higher saturated fat content, refined grains (carbohydrates), and artificial ingredients. Snack product (re)formulation using plant-based wholesome ingredients has the potential to improve health effects including glycaemia, satiety responses, and lipid metabolism. Oat (Avena sativa L.) has gained increased popularity as a food item in recent decades due to its perceived or real health benefits, principally related to the bran content of oats. We have developed a healthier snack prototype using rolled oats as main ingredients. Other ingredients include oat bran, dried fruits, and nuts. For initial trials, these ingredients were combined in various combinations and composition to produce a formula having a good nutrient profile score (≤4) that meets the criteria of FSANZ for making health-related claims. The proportions of the ingredients in the formula were adjusted to enable higher fiber and protein contents. From the initial 10 combinations prepared, one prototype was selected based on four quality attributes (visual appearance, texture, taste, and water activity). The selected prototype was tested for glycemic index (n = 10) and consumer liking (n = 67). Our preliminary results demonstrated that the prototype has a low glycemic index, favorable satiety effects compared with glucose, and has acceptable taste compared with two commercial products. This formulation will be refined further when we plan to assess its effects on glycaemia and insulin profiles. High value nutrition is the New Zealand national science challenge. An approach of developing healthier snack products with verifiable health-related claims through (re)formulation could be translated into relevant dietary changes associated with potential improvement in public health.

We have successfully synthesized Y3Fe5O12 (yttrium iron garnet, YIG) nanotubes (NTs) of different diameters using a conventional sol-gel method in anodized aluminum oxide (AAO) templates. An annealing process at 800 °C is performed to get a pure phase of YIG. The room-temperature magnetization measurements show that the coercivity decreases significantly as the diameter of nanotubes increases. The temperature dependence of magnetic moments in field-cooled (FC) and zero-field-cooled (ZFC) modes indicates that YIG NTs transform from ferromagnetic-like (FM-like) state to superparamagnetic (SPM) state when temperature decreases (in the region of 310 K–400 K). The Blocking temperature dramatically decreases as the size of YIG NTs reduces. In the FM-like state, the temperature-dependent coercivity in three different samples yields a 1/2 power law of the temperature. The temperature dependence of saturation magnetization in three different samples can be well fitted to Bloch’s T3/2 law. Characterization of ferromagnetic resonance (FMR) is conducted, which indicates the Gilbert damping parameter of YIG NTs is around 7–9 × 10−3.

We theoretically study the scattering behavior of spin waves (SWs) at the interface of an antiferromagnetically coupled (AFMC) heterojunction. It is shown that the SWs passing through the interface are evanescent and the incident waves are all reflected back, demonstrating a magnetization-dependent magnon blocking effect in this structure. We also analytically derive the expressions for the decay length of the evanescent waves (EWs). The theoretical result indicates that with the increase of the spin-wave (SW) frequency, the decay length decreases and the EWs are more concentrated at the interface, showing a magnonic skin effect (MSE) which is similar to the skin effect of electromagnetic waves. Furthermore, a positive magnonic Goos-H\"anchen shift (MGHS) of the reflected waves is also predicted. It can be understood by an effective reflection interface shift induced by the nonzero decay length of the EWs. The results of micromagnetic simulations are consistent well with all the theoretical findings. Based on the above findings, we also propose a magnon valve without spacers, which shows 100% on-off ratio for magnons. Our work provides insights into SW transmissions in the system of AFMC heterostructures and will serve as a promising tool for future magnonic devices.

The $m\phantom{\rule{0}{0ex}}e\phantom{\rule{0}{0ex}}m\phantom{\rule{0}{0ex}}o\phantom{\rule{0}{0ex}}r\phantom{\rule{0}{0ex}}y$ $w\phantom{\rule{0}{0ex}}a\phantom{\rule{0}{0ex}}l\phantom{\rule{0}{0ex}}l$, a bottleneck between storage and processor in the traditional von Neumann computing paradigm, has become increasingly serious with the rise of ``Big Data'', and there is strong interest in developing logic-in-memory computing architectures. The authors propose a skyrmion-based programmable logic device with complete Boolean logic functions, a feature that has remained elusive so far. This device can realize robust and programmable logic functions under solely electrical control, in the presence of both the inhomogeneities and thermal fluctuations that are are experimentally unavoidable. This result, then, suggests a path to overcoming the memory wall.

We design a back-illuminated p–i–n–i–n separate absorption and multiplication (SAM) AlGaN solar-blind avalanche photodiode (APD) with a low Al-content p-graded AlxGa1-xN layer and a high/low Al-content AlGaN multiplication layer. Simultaneously, an III-nitride AlN/Al0.64Ga0.36 N distributed Bragg reflector (DBR) structure is inserted to improve the solar-blind photoresponse for the designed APD. The simulation results show that the designed APD exhibits enhanced optoelectronic characteristics compared to the conventional APD, which is attributed to the higher holes impact ionization coefficient and generated polarization electric field in the same direction as the applied bias field of the designed APD. The designed APD exhibits significant enhanced avalanche gain and reduced avalanche breakdown voltage compared with the conventional APD.

The discovery of two-dimensional (2D) van der Waals (vdW) intrinsic magnets has opened a promising avenue to design high-performance magnetic tunnel junctions (MTJs) based on 2D materials. In this work, using first-principles calculations, it is demonstrated that bilayer $\mathrm{Co}{\mathrm{Br}}_{2}$ is intrinsically a magnetic semiconductor with intralayer ferromagnetic (FM) and interlayer antiferromagnetic (AFM) couplings and the interlayer AFM coupling in bilayer $\mathrm{Co}{\mathrm{Br}}_{2}$ is independent on the stacking orders. Moreover, using the nonequilibrium Green's function combined with density functional theory, it is found that due to the large difference between interlayer AFM and FM states of the $\mathrm{Co}{\mathrm{Br}}_{2}$ barrier, the conductance of spin filter (SF) vdW MTJs based on the graphene/bilayer $\mathrm{Co}{\mathrm{Br}}_{2}$/graphene heterostructure for the interlayer FM state of the $\mathrm{Co}{\mathrm{Br}}_{2}$ barrier is about 25 times that for the interlayer AFM state of the $\mathrm{Co}{\mathrm{Br}}_{2}$ barrier. Consequently, a high tunneling magnetoresistance (TMR) ratio of $2420%$ is achieved in this SF-vdW MTJ at zero bias. In particular, because the current for the interlayer FM state of the $\mathrm{Co}{\mathrm{Br}}_{2}$ barrier rapidly increases with the increase of bias voltage, a giant TMR ratio of up to about $38\phantom{\rule{0.16em}{0ex}}000%$ can be achieved in this SF-vdW MTJ at 0.2-V bias. Our results suggest that SF-vdW MTJs formed by the interlayer AFM barrier with variable conductivity hold great potential for developing vdW MTJs with a high TMR ratio.

The mixed teaching model combines the advantages of traditional teaching and network teaching in the "Internet +" era, which has become one of the important trends in the higher education teaching development. In order to follow this development trend, the human parasitology teaching team makes a reasonable use of modern information techniques, actively promotes the construction and application of online resources, and conducts mixed online and offline teaching based on MOOC resources and the experimental teaching digital platform. This mixed teaching model has shown a positive impact on both teaching and learning among teachers and students; however, students' personalized independent and deep learning remains unsatisfactory. It is suggested that the online course resources construction, teaching design and digital literacy remain to be increased, so as to create a high-level, innovative and challenging online-offline mixed "golden course".

The two-plasmon-decay instability (TPD) in the large-incidence-angle regime is studied via fluid and particle-in-cell (PIC) simulations. It is found that the TPD threshold in this regime within a narrow incidence angle range close to 60∘ can be orders of magnitude lower than the normal-incidence threshold. A threshold formula is proposed for this regime and is verified by fluid and PIC simulations. PIC simulations show significant laser absorption and energetic electron generation once TPD is excited. The incident angle and the laser spot size have a significant influence on the TPD in the large-incidence-angle regime. The low threshold and significant hot electron generation in this regime pose potentially unexpected preheating risks to inertial confinement fusion.

Self-generated magnetic fields in single-mode ablative Rayleigh–Taylor instability (ARTI) relevant to the acceleration phase of inertial confinement fusion (ICF) implosions are studied via two dimensional simulations. In ARTI, [Formula: see text] T magnetic fields can be generated via the Biermann battery source without considering the Nernst effect. The Nernst effect significantly compresses the magnetic field against the electron temperature gradient and amplifies the peak value by more than three times. A scaling law for the magnetic flux is obtained, and it well predicts the evolution of the magnetic field from linear to deeply nonlinear phases of ARTI. The self-generated magnetic field reduces the ablation near the spike and reduces the width of bubbles by magnetizing the electron heat flows, which results in higher magnitude vorticity inside the bubble and enhances the nonlinear ARTI bubble penetration velocity for short-wavelength modes. The bubble velocity boosting due to self-generated magnetic field indicates the larger impact of the short-wavelength ARTI modes on ICF implosion performance than previously expected.

We theoretically investigate the transmission of exchange-dominated spin waves in a one-dimensional magnonic crystal (MC) with a periodic exchange bias field. By recasting the Landau-Lifshitz-Gilbert equation into an effective Schr\"odinger equation and establishing spin-wave functions, it is found that MCs with upward (up) and downward (down) magnetization, respectively, correspond to the rectangular $N$-fold barriers and wells for magnons. The broadband transmission spectra in up and down states are systematically investigated. We show the phenomena of the magnon resonant transmission in both states and calculate the resonant transmission wave functions, which are related to the magnon density. Our results also show a transmission spectra shift effect (TSSE) between up and down states, which is found to be general in this system. Furthermore, the TSSE is useful to design a type of magnon valve, the magnonic-crystal-based magnon valve (MCMV), which has a large on/off ratio and bandwidth. By high-throughput screening, 125 000 groups of parameters of the MC are calculated, and 1948 parameter groups of high-performance MCMVs are screened out. Our work clarifies the physical details of the exchange-dominated spin-wave transmission in rectangular $N$-fold barriers and wells and also provides a promising route for designing novel magnonic devices.

Systematic analysis of the surface morphology, crystalline phase, chemical composition and elemental distribution along depth for nitrogen-doped niobium was carried out using different methods of characterization, including Scanning Electron Microscopy (SEM), Atomic-Force Microscopy (AFM), Grazing Incidence X-ray Diffraction (GIXRD), Rutherford Backscattering Spectrometry (RBS) and layer-by-layer X-ray Photoelectron Spectroscopy (XPS) analysis. The results showed that, after nitrogen doping, the surface was covered by densely distributed trigonal precipitates with an average crystallite size of 32 ± 8 nm, in line with the calculation result (29.9 nm) of nitrogen-enriched β-Nb2N from GIXRD, demonstrating the phase composition of trigonal precipitates. The depth analysis through RBS and XPS indicated that β-Nb2N was dominant in the topmost 9.7 nm and extended to a depth of 575 nm, with gradually decreased content. In addition, the successive change along depth in the naturally oxidized states of niobium after nitrogen doping, was revealed. It was interesting to find that the oxygen diffusion depth could be moderately enhanced by the nitridation process. These results established the near-surface phase composition of nitrided niobium, which is of great significance in evaluating the effect of nitrogen doping and further understanding the Q improvement of the superconducting radio frequency cavities.

We study magnon transmission in the sandwich structure of ferromagnetic insulators (FMIs), antiferromagnetic insulators (AFMI), and ferromagnetic insulators (FMI) by atomistic spin-model simulations. Magnon junction effects (MJEs), which have been reported in magnon junction (MJ) experiments, can be reproduced in this work, demonstrating the importance of spin-dependent magnon blocking effects (MBEs) in a MJ structure. Moreover, AFMI spacers with various structures are investigated. We show that the MJE is sensitive to the characteristics of the AFMI spacer such as orientation of N\'eel vector, types of AFMI spin configuration, and intrinsic exchange interaction. It is found that these phenomena are rooted in the magnon selection rules between two FMIs of different magnonic polarization. Based on the mechanism studied above, we further propose an in-plane MJE and give a feasible experimental prediction using nonlocal magnon-mediated current-drag measurement. Our work provides insight into magnon transmission in MJ and serves as a promising tool for future magnon circuits.

Magnetic skyrmions are topologically protected spin structures, offering great promise as information carriers for future spintronic devices. However, a series of challenges, such as unreliable skyrmion motion, pinning effects, and a weak readout signal, prevent the development of skyrmionic applications. The recently demonstrated capability to engineer the local exchange-bias field (LEBF) in an exchange-biased composite, provides solutions to these challenges. By exploiting LEBF, we design and analyze a robust skyrmion shift device. LEBF-induced magnetic domain walls form the boundary of the device channel, and LEBF potential wells are implemented in the channel for positioning skyrmions. Based on simulations with comprehensive models, we demonstrate the proposed device has the advantages of (i) localizing the skyrmions in the absence of current, (ii) suppressing skyrmion annihilation during transport, (iii) promoting steady skyrmion motion, (iv) enhancing the skyrmion velocity, and (v) magnifying the readout signal. Our results form the basis for the design of robust skyrmion devices through LEBF engineering.

With the joint efforts of countries and global non-state actors, great achievements have been made in the global malaria control programme; however, malaria remains a serious threat to human health. As the global leader for combating malaria, WHO formulated The Global Technical Strategy for Malaria 2016-2030, and the Global Malaria Programme, under the leadership of WHO, is responsible for implementing 5 key projects to achieve the goal proposed in The Global Technical Strategy for Malaria 2016-2030. In addition, the Global Fund, the U.S. President's Malaria Initiative and BillMelinda Gates Foundation also play an important role in global malaria elimination programme. This review describes the currently main non-state actors participating in the global malaria elimination programme, and calls for the enhanced inter-actor coordination and close collaboration with state governments to achieve the great goal of malaria elimination in the world.

This study aims to explore the clinical efficacy of ticagrelor combined with aspirin in patients with coronary heart disease angina pectoris and the effects on N terminal pro B type natriuretic peptide (NT-ProBNP) and creatine kinase-MB (CK-MB) levels.A total of 150 patients with coronary heart disease angina pectoris were prospectively analyzed in this study. These patients were admitted to Huaiyin Hospital of Huai'an City from February 2017 to February 2019. The patients were divided into control group and research group according to different treatment methods. The following indicators before and after treatment were observed: therapeutic efficacy, prevalence of adverse reactions, duration and frequency of angina attack, NT-ProBNP and CK-MB levels. Receiver operating characteristic (ROC) curve was used to analyze the predictive value of NT-ProBNP and CK-MB for the curative effect of coronary heart disease angina pectoris.The total effective rate in the research group was higher than that in the control group (p0.05). The prevalence of adverse reactions in the research group was lower than that in the control group (p0.05). The duration and frequency of seizures of the two groups after treatment were lower than those before treatment. The duration and frequency of seizures in the research group were lower than those in the control group (p0.05). The physiological function, physical pain, vital energy score and general health status in the research group were higher than those in the control group (p0.05). The NT-ProBNP and CK-MB levels in both groups after treatment were decreased.Ticagrelor combined with aspirin has definite therapeutic effect on patients with coronary heart disease angina pectoris, with low prevalence of adverse reactions. It can significantly reduce the levels of NT-ProBNP and CK-MB, which is worthy of promotion.

The emergence of magnetic skyrmions, topological spin textures, has aroused tremendous interest in studying the rich physics related to their topology. While skyrmions promise high-density and energy-efficient magnetic memory devices for information technology, the manifestation of their nontrivial topology through single skyrmions and ordered and disordered skyrmion lattices could also give rise to many fascinating physical phenomena, such as chiral magnon and skyrmion glass states. Therefore, generating skyrmions at designated locations on a large scale, while controlling the skyrmion patterns, is the key to advancing topological magnetism. Here, a new, yet general, approach to the "printing" of skyrmions with zero-field stability in arbitrary patterns on a massive scale in exchange-biased magnetic multilayers is presented. By exploiting the fact that the antiferromagnetic order can be reconfigured by local thermal excitations, a focused electron beam with a graphic pattern generator to "print" skyrmions is used, which is referred to as skyrmion lithography. This work provides a route to design arbitrary skyrmion patterns, thereby establishing the foundation for further exploration of topological magnetism.

Voltage-controlled magnetic anisotropy (VCMA) has attracted broad interest due to its high efficiency in switching magnetization. Large VCMA was experimentally observed in Cr/Fe/MgO junction with ultrathin Fe layer [Nozaki et al., Phys. Rev. Appl. 5, 044006 (2016)], whose underlying mechanism was still not clear however. The Cr/Fe/MgO/Fe magnetic tunnel junction (MTJ) is also well known for its quantum-well (QW) states and as-induced spin-dependent resonant tunneling [Greullet et al., Phys. Rev. Lett. 99, 187202 (2007)]. Here, in order to uncover the relation between the large VCMA and the QW states, we developed a $k$-resolved VCMA calculation method combined with the second-order perturbation theory to investigate it. We find the VCMA coefficient reaches $\ensuremath{-}297$ fJ/V m matching well with the previous experiment with three monolayers (MLs) of Fe. The coefficient oscillates strongly and even changes its sign with increasing the number of Fe MLs. Comparing the $k$-resolved VCMA with the Fermi surface of the interfacial Fe atom, the screening charges theory for VCMA was verified. For $2--9$ MLs Fe, interestingly, the QW states of ${\mathrm{\ensuremath{\Delta}}}_{1}$ electron at the $\mathrm{\ensuremath{\Gamma}}$ point provide large (no) contribution to the VCMA with odd (even) MLs. Moreover, the change of the orbital-resolved Fermi surface at the interfacial Fe atom also plays an important role on VCMA oscillation, which as well as the QW states results in the largest VCMA for 3-ML Fe. Our results deepen the understanding of the large VCMA in the Cr/Fe/MgO junction, which would be helpful to design a practical MTJ with large VCMA.

Deterministic magnetization switching driven by current-induced spin–orbit torque (SOT) without an external magnetic field has potential applications in magnetic random access memory. Here, we realized the field-free magnetization switching in a T-type structure (CoFeB/W/CoFeB), where the two CoFeB layers have perpendicular magnetic anisotropy and in-plane magnetic anisotropy (IMA), respectively. We discovered that the direction of symmetry-breaking field is parallel to the magnetization of the bottom CoFeB (IMA), which cannot be explained by a stray field of this layer. In addition, by placing a 2.5-nm thick insulating layer of MgO between the bottom CoFeB and W layer (CoFeB/MgO/W/CoFeB) to block the interlayer exchange coupling and the spin current from the bottom CoFeB, the field-free SOT switching was still achieved, primarily due to the Néel orange-peel effect in our devices. By using micromagnetic simulations, the roughness of angstrom magnitude was introduced into the model to calculate the symmetry-breaking field, finding a qualitative agreement with experiments. Moreover, we obtained the spin Hall angle of CoFeB ([Formula: see text] = −0.024) by the current-induced hysteresis loop shift method, and the contribution of the effective efficiency χ from the bottom CoFeB was accounted for about 26% of the total in the current-induced SOT switching process. These results indicated that an in-plane ferromagnet layer in the T-type structure provides not only the symmetry-breaking field but also spin current for the field-free SOT magnetization switching.

Steady high-flux helium (He) plasma with energy ranging from 50 eV to 90 eV is used to fabricate a fiber-form nanostructure called fuzz on a polycrystalline molybdenum (Mo) surface. Enhanced hydrogen (H) pulsed plasma in a wide power density range of 12 MW/m2–35 MW/m2 is subsequently used to bombard the fuzzy Mo, thereby simulating the damage of edge localized mode (ELM) to fuzz. The comparisons of surface morphologies, crystalline structures, and optical reflectivity between the original Mo and the Mo treated with various He+ energy and transient power densities are performed. With the increase of He ion energy, the Mo nano-fuzz evolved density is enlarged due to the decrease of filament diameter and optical reflectivity. The fuzz-enhanced He release should be the consequence of crystalline growth and the lattice shrinkage inside the Mo-irradiated layers (∼ 200 nm). The fuzz induced by lower energy experiences more severe melting damage and dust release under the condition of the identical transient H plasma-bombardment. The H and He are less likely to be trapped due to aggravated melting evidenced by the enhanced crystalline size and distinct lattice shrinkage. As the transient power density rises, the thermal effect is enhanced, thereby causing the fuzz melting loss to aggravate and finally to completely disappear when the power density exceeds 21 MW/m2. Irreversible grain expansion results in huge tensile stress, leading to the observable brittle cracking. The effects of transient thermal load and He ion energy play a crucial role in etching Mo fuzz during ELM transient events.

A comparative study to assess the three-body abrasive wear performance of medium-carbon dual-phase steels, obtained by the two heat treatments: quenching and partitioning (Q&P) process and low-temperature bainitic transformation, was conducted by employing a designed three-body abrasive wear method. The microstructures were examined using the optical, scanning and transmission electron microscopes. The carbon content of the retained austenite in the samples was measured by electron probe microanalysis. The results showed that the ultrafine dual-phases, consisting of martensite/bainite and retained austenite, were obtained in both the heat treatments. Both the samples were observed to be extremely hard (458–471 HV1). The results of the three-body abrasive wear tests indicated that the abrasion weight loss decreased as the surface hardness increased. Further, compared to the low temperature transformed bainitic sample, the Q&P treated martensitic sample had a higher retained austenite stability, superior transformation-induced plasticity effect and thicker deformed layer which showed a better three-body abrasive wear performance.