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Temperature dependence of magnetization reversal mechanism in CoNi/CoO bilayers

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Journal of Shanghai University(English Edition) 2007年第6期11卷 562-565页

作者：宋金涛袁淑娟 Library Fudan University 2.Department of Physics College of SciencesShanghai University

Exchange coupling and magfietization reversal mechanism in two series of CoxNil-x/CoO （30 nm）（x=0.2 and 0.4） bilayers are studied by vector magnetometer. Two components of magnetization are measured parallel and perpendicular to the applied field. At low temperatures, coercivity Hc oc （tFM）^-n, n = 1.5 and 1.38 for x = 0.2 and 0.4, respectively, in agreement with the random field model. At room temperature, the coercivity is nearly proportional to the inverse FM layer thickness. In addition to the exchange field and the coercivity, the characteristic of the magnetization reversal mechanism was found to change with temperature. At temperatures below 180 K, magnetization reversal process along the unidirectional axis is accompanied only by nucleation and pinning of domain wall while magnetization rotation is also involved at high temperatures.

关键词： exchange coupling bilayer magnetization reversal temperature dependence.

各向同性体积膨胀导致的双层条结构大挠度弯曲

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Acta Mechanica Sinica 2023年第5期39卷 115-122页

作者：曹圃瑜徐彦陈彬 Department of Engineering Mechanics Zhejiang UniversityHangzhou310058China School of Aeronautics and Astronautics Zhejiang UniversityHangzhou310058China

传统双层材料的弯曲理论主要针对小变形、线弹性材料.这里我们研究了双层条的大变形弯曲,建立了一个描述双层条大变形弯曲的理论.理论中假设双层条由一个主动层和一个被动层组成,只有主动层会产生各向同性体积膨胀.分析表明我们的理论... 详细信息

传统双层材料的弯曲理论主要针对小变形、线弹性材料.这里我们研究了双层条的大变形弯曲,建立了一个描述双层条大变形弯曲的理论.理论中假设双层条由一个主动层和一个被动层组成,只有主动层会产生各向同性体积膨胀.分析表明我们的理论预测与有限元模拟符合较好,而在某些情况下会与传统理论预测有明显的差异.我们理论分析还表明,存在能使双层条得到最大曲率的最佳模量比及厚度比.我们的理论可促进软质双层条带材的设计,可广泛用于多个领域.

关键词： Large deformation bilayer Soft Volumic expansion

A kinetic model for the effects of vanadate on human erythrocyte membrane

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Science China Chemistry 1999年第5期42卷 543-551页

作者：张天蓝王夔 Department of Bioinorganic Chemistry and Inorganic Pharmaceutical Chemistry Beijing Medical University Beijing China National Research Laboratories of Natural and Biomimetic Drugs Beijing Medical University Beijing China

The effects of vanadate on human erythrocyte membrane have been investigated with stopped-flow and equilibrium fluorescence quenching techniques. The equilibrium study showed a half-quenching concentration(K 1/2 ) of 0.27 mmol.L-1. The stopped-flow experiment exhibited a fast rise (tsk1/f1 S) and a slow drop (tin 1~2 min) in fluorescence. Based on the results and that from the across membrane transport of vanadate, a kinetic model is proposed which suggests that the membrane proteins experience a series of conformational changes before and during the quenching of the intrinsic fluorescence. These changes are induced mainly by three kinds of interactions: (i) the long-distance, non-specific interaction between the vanadate and the erythrocyte membrane surface, (ii) the charge interaction between the vanadate and parts of the membrane proteins, and(iii) the binding of the vanadate to some membrane proteins.

关键词： vanadate human erythrocyte membrane membrane protein lipid bilayer stopped-flow.

Influences of the Structure of Lipids on Thermal Stability of Lipid Membranes

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Communications in Theoretical Physics 2015年第8期64卷 249-258页

作者：海楠楠周昕黎明 School of Physics University of Chinese Academy of Sciences

The binding free energy(BFE) of lipid to lipid bilayer is a critical factor to determine the thermal or mechanical stability of the bilayer. Although the molecular structure of lipids has significant impacts on BFE of the lipid, there lacks a systematic study on this issue. In this paper we use coarse-grained molecular dynamics simulation to investigate this problem for several typical phospholipids. We find that both the tail length and tail unsaturation can significantly affect the BFE of lipids but in opposite way, namely, BFE decreases linearly with increasing length, but increases linearly with addition of unsaturated bonds. Inspired by the specific structure of cholesterol which is a crucial component of biomembrane, we also find that introduction of carbo-ring-like structures to the lipid tail or to the bilayer may greatly enhance the stability of the bilayer. Our simulation also shows that temperature can influence the bilayer stability and this effect can be significant when the bilayer undergoes phase transition. These results may be helpful to the design of liposome or other self-assembled lipid systems.

关键词： lipid bilayer thermal stability coarse-grained MD

Self-organized metal-semiconductor epitaxial graphene layer on off-axis 4H-SiC（0001）

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Nano Research 2015年第3期8卷 1026-1037页

作者： Debora Pierucci Haikel Sediri Mahdi Hajlaoui Emilio Velez-Fort Yannick J. Dappe Mathieu G. Silly Rachid Belkhou Abhay Shukla Fausto Sirotti Noelle Gogneau Abdelkarim Ouerghi CNRS- Laboratoire de Photonique et de Nanostructures Route de Nozay 91460 Marcoussis France Synchrotron-SOLEIL Saint-Aubin BP48 F91192 Gifsur Yvette Cedex France Universite Pierre et Marie Curie (CNRS - IMPMC) 4 PI. Jussieu 75005 Paris France Service de Physique de rEtat Condense (CNRS URA2464) IRAMIS CEA Saclay 91191 Gif-Sur-Yvette France

The remarkable properties of graphene have shown promise for new perspectives in future electronics, notably for nanometer scale devices. Here we grow graphene epitaxially on an off-axis 4H-SiC（0001） substrate and demonstrate the formation of periodic arrangement of monolayer graphene on planar （0001） terraces and Bernal bilayer graphene on （1120） nanofacets of SiC. We investigate these lateral superlattices using Raman spectroscopy, atomic force microscopy/ electrostatic force microscopy （AFM/EFM） and X-ray and angle resolved photoemission spectroscopy （XPS/ARPES）. The correlation of EFM and ARPES reveals the appearance of permanent electronic band gaps in AB-stacked bilayer graphene on （1120） SiC nanofacets of 150 meV. This feature is confirmed by density functional theory （DFT） calculations. The charge transfer between the substrate and graphene bilayer results in an asymmetric charge distribution between the top and the bottom graphene layers opening an energy gap. This surface organization can be thus defined as self-organized metal-semiconductor graphene.

关键词： epitaxial graphene layer monolayer bilayer band gap opening Bernal stacking off-axis silicon carbide electronic properties

Deformation, failure and removal mechanisms of thin film structures in abrasive machining

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Advances in Manufacturing 2017年第1期5卷 1-19页

作者： Cheng-Wei Kang Han Huang School of Mechanical and Mining Engineering TheUniversity of Queensland Brisbane QLD 4072 Australia

Thin film structures are becoming increasingly more important for industrial applications such as the making of solar panels, microelectronic devices and micro systems. However, the challenges encountered in the machining of thin film structures have been a bottleneck that impedes further wide spread uses of such structures. The development of material removal processes that are capable of producing a damage free surface at high removal rates is critical for cost effective production. Such development relies highly on a comprehensive understanding of the deformation, failure and removal mechanisms of thin film structures involved in mechanical loading. In this paper, the current understanding of the deformation characteristics of thin film systems was reviewed to provide important insights into the interracial failure under mechanical loading, with focuses on the interfacial failure mechanisms and existing problems in the machining of thin film structures. The key characterization techniques were outlined. In particular, the recent progress in the abrasive machining of a thin film multilayer structure was summarized. The potential research directions were also presented in the end of the review.

关键词： Abrasive machining Thin film bilayer Multilayer Interface Deformation Failure

Enhanced Performance of a Monolayer MoS_2/WSe_2 Heterojunction as a Photoelectrochemical Cathode

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Nano-Micro Letters 2018年第4期10卷 52-60页

作者： Jingwei Xiao Yu Zhang Huanjun Chen Ningsheng Xu Shaozhi Deng State Key Laboratory of Optoelectronic Materials and Technologies Guangdong Province Key Laboratory of Display Material and Technology School of Electronics and Information Technology Sun Yat-sen University

Transition-metal dichalcogenide(TMD) semiconductors have attracted interest as photoelectrochemical(PEC) electrodes due to their novel band-gap structures,optoelectronic properties, and photocatalytic ***, the photo-harvesting efficiency still requires improvement. In this study, A TMD stacked heterojunction structure was adopted to further enhance the performance of the PEC cathode. A P-type WSe_2 and an N-type Mo S_2 monolayer were stacked layer-by-layer to build a ultrathin vertical heterojunction using a micro-fabrication *** situ measurement was employed to characterize the intrinsic PEC performance on a single-sheet *** from its built-in electric field and type II band alignment, the MoS_2/WSe_2 bilayer heterojunction exhibited exceptional photocatalytic activity and a high incident photo-to-current conversion efficiency(IPCE). Comparing with the monolayer WSe_2 cathode, the PEC current and the IPCE of the bilayer heterojunction increased by a factor of 5.6 and enhanced 50%, respectively. The intriguing performance renders the MoS_2/WSe_2 heterojunction attractive for application in high-performance PEC water splitting.

关键词： MoS2/WSe2 Monolayer bilayer Heterojunction Photoelectrochemical cathode

Interlayer Coupling of Co/NM/FM(NiFe and Co) Nano-Sandwich Films

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Chinese Journal of Aeronautics 2003年第4期16卷 253-256页

作者：马晓艳毕晓昉宫声凯徐惠彬 Department of Materials Science and Engineering Beijing University of Aeronautics and Astronautics Beijing 100083 China

Cu/Co, Cu/NiFe, Ta/NiFe bilayers and Co/Cu/Co, Co/Cu/NiFe, Co/Ta/NiFe sandwich films were deposited by a magnetron sputtering method. Magnetic properties were evaluated by VSM and spin valve magnetoresistance was investigated by a four-probe method to study the interlayer coupling of the two magnetic layers. It has been found that the interlayer coupling depended not only on the layer thickness of the nonmagnetic spacer but also on the nature of the spacer. The interlayer coupling was reduced as the spacer layer thickness increased. The result was consistent with those from observations of the magnetic domain for the trilayers by means of Lorentz Electron Microscope. The trilayers with Cu spacer layer have shown a stronger coupling than those with Ta spacer layer.

关键词： bilayer trilayer interlayer coupling nonmagnetic spacer domain observation

Enhanced Tribological Performance of Diamond Films by Utilizing DLC and DLC-H Top Layers

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Journal of Shanghai Jiaotong university(Science) 2023年第5期28卷 665-675页

作者：雷学林严莹张航李子璇何云 School of Mechanical and Power Engineering East China University of Science and TechnologyShanghai 200237China

High-performance diamond films are highly demanded on tool surfaces for wire-drawing and mechanical sealing ***,this work aims at enhancing the tribological performance of chemical vapor deposition diamond films in water-lubricated conditions by utilizing non-hydrogenated and hydrogenated diamond-like carbon(DLC and DLC-H)top *** tribological properties of bilayer micro-crystalline diamond(MCD)/DLC,MCD/DLC-H,nano-crystalline diamond(NCD)/DLC and NCD/DLC-H films are evaluated,in terms of maximal and stable coefficients of friction(COFs),C—C bonds transformation,worn surface morphology and specific wear *** results show that DLC or DLC-H coated on diamond layer significantly suppresses the initial maximal COF peak and the wear of counterpart ***,severe regular arranged sp^(2) C—C bonds transformation is detected on MCD film,in comparison to NCD;while inversely,the NCD/DLC bilayer exhibits severer C—C bonds transformation effect compared with the MCD/***,the DLC-H top layer shows a larger decreasing rate of maximal COFs and wear rates of counterpart balls,compared with the DLC coating,which is due to its superior *** all the tested films,the NCD/DLC-H bilayer shows an optimized tribological performance.

关键词： diamond film diamond-like carbon(DLC) bilayer tribology