First-principles study on transport properties of zigzag graphene nanoribbon with different spin-configurations

The current-voltage (I-V) characteristics and the transmission spectrums of zigzag graphene nanoribbon with different spin-configurations are investigated by using the first-principles calculations. It is shown that the current-voltage curves and the transmission spectrums strongly depend on the spin-configurations of the two sides of the ribbon. For the spin-parallel configuration structure, the curve is linear under lower bias voltage; For the spin-antiparallel configuration structure, there is a strong spin-polarization-dependent transmission which implies the ribbon can be used as a spin filter; while for other spin-configurations structures, the curve has the characteristic of semiconductor. It is found that there is a large magneto-resistance(MR) when the bias voltage is small. The impurity in the central scattering region significantly influences the spin-dependent current and the spin filter efficiency, which may lead the large MR to disappear.     

MgSe薄膜的相结构研究

我们采用ＭＯＣＶＤ外延技术首次在ＧａＡｓ（１００）和（１１１）衬底上成功地生长了ＭｇＳｅ单层薄膜．利用Ｘ射线衍射技术观察到了它的ＮａＣｌ结构、纤锌矿结构和闪锌矿结构三种相结构，并首次实验测量出了闪锌矿结构ＭｇＳｅ的晶格常数     

240mm厚混凝土小砌块砌体房屋设计技术

介绍了利用新型砌块２４０ｍｍ厚混凝土小型空心砌块建造承重墙或作为多层房层外墙时，有关砌体设计和构造建设的技术和要求。最新提出了在Ｕ型砌块内放置水平钢筋现浇混凝土以形成墙内钢筋混凝土水平浇带的技术设想。     

从企业结构调整与优化角度理解企业信息化建设

企业结构调整与优化是新时期企业形成市场竞争有时必须面对的问题。企业信息化建设是企业结构与调整的重要组成内容。本文讨论了信息企业化建设对企业结构调整与优化的重要作用,介绍了在企业结构调整与优化中企业信息化建设应解决的问题及任务。     

在我国申请的无取向电工钢专利技术的分析

1985年至2005年,在我国申请的无取向电工钢专利中,国外厂家有44件,主要为JFE和新日铁;国 内厂家有48件,主要为宝钢和武钢。国外厂家申请的电工钢专利技术领域主要为高效化和涂层技术;国内厂家主 要为轧制工艺和涂层技术。无取向电工钢的典型专利技术：有高效化,薄带连铸、涂层、加工工艺和半工艺产品;无 取向电工钢发展趋势为产品高效化和特殊用途产品。     

GaN的RBS/沟道、X射线双晶衍射和光致发光谱

采用卢瑟福背散射及沟道效应、X射线双晶衍射和光致发光谱三种技术对两类未故意掺杂的MOVPE生长的GaN样品进行综合测试.它们在表征GaN单晶膜质量方面结果一致.     

掺有BN纳米点石墨烯纳米带的电子结构和输运性质的第一性原理研究

利用第一性原理研究了含有BN纳米点的扶手椅型石墨烯纳米带的电子结构和输运性质。研究发现,能带结构与BN纳米点的几何形状、尺寸以及纳米点浓度密切相关。由于电子-空穴对的对称性,使得费米能级附近的价带和导带几乎关于费米能级是对称的。对于含有三角形BN纳米点的石墨烯纳米带,当B和N交换时,价带和导带正好关于费米能级相互倒置。而且,由于C原子和多余B原子(或多余N原子)之间的轨道杂化,使得在费米能级附近形成一条局域的能带。另外,当电子在含有BN纳米点的石墨烯纳米带中输运时,在电导谱中会出现一系列的共振峰,其依赖于BN纳米点之间的距离和纳米点的形状。由此通过控制这些参数可以调制系统的电子响应。     

First-principles study on transport properties of zigzag graphene nanoribbon with different spin-configurations

The current-voltage(I-V) characteristics and the transmission spectra of zigzag graphene nanoribbon with different spin-configurations are investigated by using first-principles calculations.It is shown that the I-V curves and transmission spectra strongly depend on the spin-configurations of the two sides of the ribbon.For the spin-parallel configuration structure,the curve is linear under lower bias voltage;for the spin-antiparallel configuration structure,there is a strong spin-polarization-dependent transmission which implies that the ribbon can be used as a spin filter;while for other spin-configuration structures,the curve has the characteristics of a semiconductor. It is found that there is a large magneto-resistance(MR) when the bias voltage is small.The impurity in the central scattering region significantly influences the spin-dependent current and the spin filter efficiency,which may lead the large MR to disappear.     

一种新型多模干涉型光子晶体波分解复用器

基于二维光子晶体中多模干涉效应（MMI）设计了一种新型的三波长波分解复用器,该结构能有效分离1310/1500/1550nm三个波段的波长。并且,当我们改变该波分解复用器的相关结构参数时,该结构能拓展至其他波段。除此之外,该结构也能单独作为两波长波分解复用器对1310/1550nm实现分离。通过计算,该波分解复用结构三个波长的透射率均在91%以上。与此同时,借助于平面波展开法及时域有限差分法,我们对光波在该结构的传播效率及传播行为进行了计算及模拟。