Quenching of the Haldane gap in LiVSi<Subscript>2</Subscript>O<Subscript>6</Subscript> and related compounds

We report results of susceptibility χ and ⁷Li NMR measurements on LiVSi₂O₆. The temperature dependence of the magnetic susceptibility χ(T) exhibits a broad maximum, typical for low-dimensional magnetic systems. Quantitatively it is in agreement with the expectation for an S=1 spin chain, represented by the structural arrangement of V ions. The NMR results indicate antiferromagnetic ordering below T_N=24 K. The intra- and interchain coupling J and J_p for LiVSi₂O₆, and also for its sister compounds LiVGe₂O₆, NaVSi₂O₆ and NaVGe₂O₆, are obtained via a modified random phase approximation which takes into account results of quantum Monte Carlo calculations. While J_p is almost constant across the series, J varies by a factor of 5, decreasing with increasing lattice constant along the chain direction. The comparison between experimental and theoretical susceptibility data suggests the presence of an easy-axis magnetic anisotropy, which explains the formation of an energy gap in the magnetic excitation spectrum below T_N, indicated by the variation of the NMR spin-lattice relaxation rate at T≪T_N.     

Magnetic fabrics in fault-related fold and its relation with finite strain: an example from Mingjiang thrust structures in Western Sichuan

The anisotropy of magnetic susceptibility (AMS) is a quick, effective and sensitive technique used to measure the weakly deformed sedimentary rocks, and also a reliable method to reveal the deforming mechanisms of fault-related folds. In Longmenshan front belt, a typical cross-section of fault-related folds is chosen to study the AMS. A total of 224 oriented specimens have been drilled at 23 different sampling sites which were distributed at the key structural positions of this structural section developed in the Xujiahe formation of the upper Triassic. Six elementary types of magnetic fabrics are recognized and established through this AMS study: 1) a sedimentary fabric; 2) an initial deformation fabric; 3) a pencil structure fabric; 4) a weak cleavage fabric; 5) a strong cleavage fabric; 6) a stretching lineation fabric. It has been found that most of magnetic fabrics are characterized by fabrics of weak deformation which belong to the pure-shear results of a pre-folding layer parallel shortening (LPS). In the fault-bend fold, almost all magnetic fabrics are the initial deformation fabrics of weak deformation, and denote that the deformation in the forelimb is stronger than that in the backlimb and no finite strain is shown in the footwall. While in the fault-propagation fold， finite strains are concentrated in the trishear zone where magnetic fabric results are approximately consistent with the estimated consequences of the kinematic model. The tectonic stress field indicated by the magnetic fabrics is basically the same along the whole structural section and shows a NW to SE compression and shortening which is accordant with the regional compressive stress field of the Longmenshan fold-thrust belt.     

Functional Materials for Catalytic and Magnetic Applications

1 Introduction Metal, metal oxide and metal compound nanoparticles (NPs) received considerable attention due to their unique properties: catalytic, magnetic, optical, electronic, etc. We believe that for different applications, there are preferable morphologies of NP-stabilizing medium composites. For example, small (1-3 nm) nanoparticles formed in micro/mesoporous hypercrosslinked polystyrene demonstrate excellent catalytic properties in various hydrogenation and oxidation reactions due to high surface...     

X射线磁性圆二色吸收谱:实验设备与初步实验

合肥国家同步揭射实验室已建立了初步的X射线磁性圆二色吸收谱（XMCD）技术，可以测量铁磁性3d过渡族元素Fe，Co和Ni的L边的XMCD，并获得它们的轨道和自旋磁矩．XMCD线站的主要技术参数为：能量范围100～1000eV，光子通量≈10^8 ph／s，能量分辨率≈1000；外磁场1500Gs.除了测量XMCD外，还可以测量C，N，O的K边近边吸收谱，以及部分元素的L边近边吸收谱．     

Magnetism in Mn and Co doped ZnO bulk samples

Bulk samples with nominal composition Zn0.95Co0.05O and Zn0.92Co0.05Mn0.03O were fabricated by a solid-state reaction method at 600℃.X-ray diffraction experiment showed that the peaks of secondary phase Co3O4 with a cubic structure were visible in both samples,besides the main peaks of wurtzite structure as ZnO.Magnetization measurement indicated that doping Co alone can induce ferromag- netism in ZnO itself,while the introduction of Mn significantly enhances ferromagnetism.However, both samples showed different magnetic behavior at temperatures below 50 K.It was also noted that ferromagnetic coupling interaction was weakened due to the presence of antiferromagnetic Co3O4.     

玉叶金花(Mussaenda pubescens)SSR引物的快速开发

利用链亲和素磁珠吸附法捕捉能与生物素标记的探针(AC)15退火结合的玉叶金花(Mussaenda pu-bescens)微卫星序列的单链限制性酶切片段.获得的单链目的片段,经PCR扩增形成双链,然后克隆到pGEMT载体上,转化至DH5α中,得到一个微卫星序列文库.经测序统计,引物得率为12.5%;根据序列设计的SSR两侧引物PL和PR,共得到5对有多态性的SSR引物.玉叶金花微卫星引物的筛选将为下一步进行玉叶金花基因组结构的分析、分子进化和系统发育研究提供重要的微卫星标记.     

一种研究自旋翻转散射效应的新方法

金属中自旋翻转散射长度远长于电子平均自由程，近来关于自旋翻转散射效应的研究主要集中于扩散区域．文章作者提出了一种使用双势垒磁性隧道结来研究纳米尺度结构中弹道区域的自旋翻转散射效应的新方法．这种方法可以从磁电输运性质的测量，得出中间隔离层中的自旋翻转散射效应的温度和偏压关系，进一步可以得出诸如电子平均自由程和自旋翻转散射长度等自旋散射信息，以及中间层的态密度和量子阱信息．     

钕铁硼在高温超导磁悬浮技术实验中的应用

将新材料钕铁硼作为磁导轨引入到高温超导磁悬浮技术实验中,介绍了高温超导悬浮技术实验的基本原理、仪器及钕铁硼对实验的改进.     

高温超导体环流演示仪

利用永磁铁对超导样品进行激励,产生的超导环流不衰减,由此原理制做了高温超导环流演示仪,该仪器可演示零电阻现象、环流磁场及超导体电阻与温度的关系.     

磁场中夸克物质的黏滞系数

研究了磁场中夸克非轻子弱作用过程的反应率和黏滞系数. 改进了在弱磁场情况下的近似计算方法, 给出了非轻子过程的反应率与夸克物质的体黏滞系数的表达式, 显示出在弱磁场情况下, 黏滞系数的温度依赖关系与零磁场情况下一致, 但黏滞系数的大小依赖磁场的强度.