电流调控磁涡旋的极性和旋性

提出了一种特殊自旋阀结构, 其极化层(钉扎层)磁矩沿面内方向, 自由层磁矩成磁涡旋结构. 自由层在形状上设计成左右两边厚度不同的阶梯形圆盘. 微磁学模拟研究发现, 通过调控所施加的高斯型脉冲电流的大小、方向和脉冲宽度, 可以实现磁涡旋的不同旋性、不同极性的组态控制. 分析了该结构中电流调控磁涡旋旋性和极性的物理原因和微观机理.     

亚热带3个地点青钱柳群落特征比较

【目的】以亚热带3个区域青钱柳天然群落为研究对象,通过调查其物种组成、结构特征、种群结构以及更新状况,探究影响青钱柳种群更新的主要原因,为青钱柳野生资源的保护和可持续利用提供科学依据和技术支撑。【方法】采用典型样方调查的方法,对3个青钱柳群落[四川沐川(群落M)、广西金钟山(群落J)和湖北鹤峰(群落H)]进行样方调查,分析其物种组成、物种多样性特征和区系特征,并评价群落间的相似性。以径级代替年龄的方式分析种群结构和更新情况。【结果】四川沐川群落(群落M)、广西金钟山群落(群落J)和湖北鹤峰群落(群落H)分别有维管植物32科50属70种、50科79属96种和59科100属126种;3个群落区系特征差异不显著,均以亚热带和温带成分为主;物种多样性和物种丰富度变化趋势较为一致,表现为乔木层>灌木层>草本层。3个群落的物种多样性和丰富度总体表现为群落H>群落J>群落M;群落结构为中等不相似,相似度表现为群落M与群落J的较高,群落M与群落H的次之,群落J与群落H的较小。【结论】整体来看,不同地理分布的青钱柳群落物种组成差异明显,相似性水平低,但其结构特征具有一定的相似性;乔木层树种优势显著,导致林分郁闭,林下光照减少,影响种群更新;灌木层植物种类较多,分布较为均匀;草本层占据较少空间,以蕨类植物为主;青钱柳种群天然更新在径级结构上出现不同程度的残缺现象,导致更新不连续。从天然更新的角度看,适当开辟林窗,有利于促进林下青钱柳幼苗幼树的生长及均匀分布,完成种群更新,使群落向着长久稳定的方向发展。     

Micromagnetic simulation for high field sensors with perpendicular magnetizations

In this paper, we present a micromagnetic design for high field sensors. The hard layer of the sensors is L1垂直磁化;强磁场传感器;微磁学模拟;高巨磁阻效应micromagnetic simulation, giant magnetoresistive, coercivity, demagnetizing fieldProject supported by the Nature Science Foundation of China (Grant No~10404019) and by the Science and Technology Committee of Shanghai (Grant No~05PJ14090).2006-09-232006-11-28In this paper, we present a micromagnetic design for high field sensors. The hard layer of the sensors is L1垂直磁化;强磁场传感器;微磁学模拟;高巨磁阻效应micromagnetic simulation, giant magnetoresistive, coercivity, demagnetizing fieldProject supported by the Nature Science Foundation of China (Grant No~10404019) and by the Science and Technology Committee of Shanghai (Grant No~05PJ14090).2006-09-232006-11-28In this paper, we present a micromagnetic design for high field sensors. The hard layer of the sensors is L10-FePt which is magnetized perpendicularly to film plane and the sense layer is NiFe which is magnetized in the film plane. The magnetization configurations of the hard and sense layers at different external magnetic fields have been simulated. In micromagnetic simulation, the sense field up to one tesla can be reached by using this sensor. We find that whether the sensor has a symmetric or an asymmetric field-sensing window is determined by the coercive field of the hard layer and the demagnetizing field of the sense layer.Corresponding author. E-mail： yaowen@mail.tongji.edu.cn/qk/85823A/200706/24631993.html7000, 7500, 7570P, 7540Mhttp://cpb.iphy.ac.cn/CN/10.1088/1009-1963/16/6/042https://cpb.iphy.ac.cn/CN/article/downloadArticleFile.do?attachType=PDF&id=1092012006-09-23In this paper, we present a micromagnetic design for high field sensors. The hard layer of the sensors is L10-FePt which is magnetized perpendicularly to film plane and the sense layer is NiFe which is magnetized in the film plane. The magnetization configurations of the hard and sense layers at different external magnetic fields have been simulated. In micromagnetic simulation, the sense field up to one tesla can be reached by using this sensor. We find that whether the sensor has a symmetric or an asymmetric field-sensing window is determined by the coercive field of the hard layer and the demagnetizing field of the sense layer.     

基于PC的嵌入式柔性智能测控技术

介绍了目前发展比较迅速的智能测控技术状况,提出了基于PC的嵌入式柔性智能测控的概念,并且研究了基于此项技术的控制器的设计方法和开发模型.     

An Effective Three-Dimensional Micromagnetic Method and Its Application to Magnetic Tunnel Junctions

An effective three-dimensional micromagnetic method for predicting equilibrium configuration of magnetization states is presented with conjugate-gradient technique to minimize the total energy, which has a much faster convergence rate than that of the quasi-Newton method. As an application, magnetic tunnel junctions with pinholes in the ultrathin barrier are simulated. The calculated coupling field Hf increases with the pinhole density increase, corresponding to the decrease of barrier thickness. The free layer domain configuration of tunnel junction during the switching process is also demonstrated.     

从养羊为过年到中国百县优势特色经济县——横山县六十年养羊业发展巡礼

横山县地处毛乌素沙漠与黄土高原的接壤地带,是西北农牧条件较好的地区,可谓草木茂盛,地肥水美,有悠久的畜牧业生产历史。其畜牧资源比较丰富。养羊是横山的传统产业,是陕西主要养羊区和毛、绒、皮、肉生产基地。可是,新中国成立前夕,毛乌素沙漠南侵,     

顺铂水溶液降解产物-羟桥双核铂(Ⅱ)化合物的制备和结构

 制备抗癌药顺铂和卡铂在水溶液中的降解产物-羟桥双核铂(Ⅱ)化合物,研究其化学结构.以顺铂为起始原料,通过水合和313nm紫外光照射,分离出目标化合物.通过测定铂含量,ESI-MS,¹H NMR和单晶X衍射分析测定其结构.所得到的化合物为以羟基搭桥的双核铂(Ⅱ)配合物,中心离子与2个氮原子和2个氧原子组成平面正方形,2个中心离子之间的距离为0.3095nm,有弱作用.2个配位平面的二面角为2.7°,几乎处于同一平面.2个硝酸根处于配位的外界.     

佛山市城市森林生态系统服务价值估算研究

以佛山市城市森林为研究对象,参照国家林业局《森林生态系统服务功能评估规范》评估方法对佛山城市森林进行估算.结果表明:2015-2016年度佛山市森林生态服务总价值为77.76亿元/a,单位面积生态服务价值为13.32万元/(hm~2·a),对生态服务功能价值贡献从大到小依次为涵养水源、固碳释氧、保育土壤、生物多样性保护、净化大气环境、积累营养物质,分别占总生态服务价值的54.60%,18.54%,13.28%,9.28%,3.49%,0.80%,涵养水源和固碳释氧是佛山城市森林最主要的生态服务功能.通过量化森林生态服务功能,为佛山城市林业发展和生态补偿提供决策依据,从而推动区域绿色生态文明建设,同时提出科学布局环境功能林对维护区域可持续发展有重要意义.     

三轴试验下二八灰土强度的变化规律

对二八灰土进行室内强度试验,分析养护龄期、含水量及浸水次数对灰土强度特性的影响.从灰土的微观机理入手对土体强度的两个指标c、φ进行分析.结果表明:灰土的养护龄期必须满足90 d才能达到其应有强度,90 d后也会有一定增长,但增长量较小;浸水对灰土的c、φ值影响显著,首次浸水使内聚力c值下降较大,以后浸水对c值影响甚微.与此不同,内摩擦角在数次浸水后(试验中为4次)才趋于稳定.     

O5+离子与He原子碰撞引起的可见光发射

用光学方法测量了O⁵⁺离子(4.06～5.31 kev·amu^-1)与He原子碰撞引起的200～800nm波长范围的可见光发射谱。分析表明,在O⁵⁺与He碰撞中存在着入射离子的单电子俘获激发和双电子俘获激发以及靶原子直接激发过程,并且有较高nl态间的跃迁。经计算得到了各发射谱线的绝对发射截面,并探讨了这些发射截面与入射离子能量之间的依赖关系。