Spin-polarized transport through the T-shaped double quantum dots

Using the Keldysh nonequilibrium Green function and equation-of-motion technique, this paper investigates the spin-polarized transport properties of the T-shaped double quantum dots （DQD） coupled to two ferromagnetic leads. There are both Fano effect and Kondo effect in the system, and due to their mutual interaction, the density of states, the current, and the differential conductance of the system depend sensitively on the spin-polarized strength. Thus the obtained results show that this system is provided with excellent spin filtering property, which indicates that this system may be a candidate for spin valve transistors in the spintronics.     

旁耦合于介观环与铁磁电极量子点系统中的自旋极化输运

借助单杂质Anderson模型哈密顿量,及利用格林函数和运动方程等理论,研究旁耦合于介观环和铁磁电极的量子点系统中的极化输运特性.结果表明,通过调节点-环耦合强度、铁磁电极中的极化强度、磁矩相对取向及温度等,均能实现控制体系中自旋极化电流的目的,达到自旋阀效应.为此系统作为一种新的自旋电子材料提供理论依据.     

氧化物气凝胶高温红外改性研究

氧化物气凝胶是一类具有超低热导率的新型纳米多孔材料,在航空航天等高温隔热领域具有广阔的应用前景。然而目前常见的氧化硅、氧化铝等氧化物气凝胶受材料/结构单元固有性质的限制,其通常具有红外透明性,而高温下辐射传热占据主导地位,大量红外辐射会透过气凝胶,热导率急剧攀升,导致其高温隔热性能较差,因此需要对其进行高温红外改性,从而满足更高的隔热性能需求。本文综述了近年来添加遮光剂、纤维及调整气凝胶的结构/形貌在提高氧化物气凝胶高温隔热性能方面的研究进展,并对未来研究方向进行展望。     

Spin-dependent transport through an interacting quantum dot system

Using an equation of motion technique, we report on a theoretical analysis of transport characteristics of a spin-valve system formed by a quantum dot coupled to ferromagnetic leads, whose magnetic moments are oriented at an angle θ with respect to each other, and a mesoscopic ring by the Anderson Hamiltonian. We analyse the density of states of this system, and our results reveal that the density of states show some noticeable characteristics depending on the relative angle θ of magnetic moment M, and the spin-polarised strength P in ferromagnetic leads, and also the magnetic flux Φ and the number of lattice sites N_R in the mesoscopic ring. These effects might have some potential applications in spintronics.     

一道高考选择题的课堂探讨

在讲解高二数学《含绝对值的不等式》练习题中,偶遇一道2006年全国Ⅱ(理)高考选择题:函数f(x)=(?)|x-n |的最小值为()(A)190.(B)171.(C)90.(D)45.本题既求和又求最值,而且与函数挂钩,学生初次遇见,确有难度.根据批阅统计,做出本题的学生占全班15%,于是我在讲解时,放慢了速度.首先了解学生对该题的认识,我让做出这道     

浅议水泥搅拌桩在高速公路软基处理中的应用

实例表明,水泥搅拌桩应用于高速公路软基处理时,须重视几个关键性参数的择取及直接影响软基处理效果的几点重要关系。     

Synthesis and electrical characterization of tungsten oxide nanowires

Tungsten oxide nanowires of diameters ranging from 7 to 200~nm are prepared on a tungsten rod substrate by using the chemical vapour deposition (CVD) method with vapour--solid (VS) mechanism. Tin powders are used to control oxygen concentration in the furnace, thereby assisting the growth of the tungsten oxide nanowires. The grown tungsten oxide nanowires are determined to be of crystalline W₁₈O₄₉. I--V curves are measured by an \textit{in situ} transmission electron microscope (TEM) to investigate the electrical properties of the nanowires. All of the I--V curves observed are symmetric, which reveals that the tungsten oxide nanowires are semiconducting. Quantitative analyses of the experimental I--V curves by using a metal--semiconductor--metal (MSM) model give some intrinsic parameters of the tungsten oxide nanowires, such as the carrier concentration, the carrier mobility and the conductivity.     

Spin-flip process through double quantum dots coupled to two half-metallic ferromagnetic leads

We investigate the spin-flip process through double quantum dots coupled to two half-metallic ferromagnetic leads in series. By means of the slave-boson mean-field approximation, we calculate the density of states in the Kondo regime for two different configurations of the leads. It is found that the transport shows some remarkable properties depending on the spin-flip strength. These effects may be useful in exploiting the role of electronic correlation in spintronics.     

面向柔性超级电容器的凝胶电解质研究进展

柔性超级电容器卓越的功率密度和柔性应用能力与可穿戴设备对柔性电源的紧迫需求相吻合,同时具备较大的能量密度提升潜力,使其受到了广泛关注。将水、有机液体、离子液体和导电离子等溶入三维聚合物网络构建导电凝胶作为电解质,不仅简化了柔性超级电容器结构,还通过引入多样的交联方式和合成材料进一步提升其性能,已成为近年备受瞩目的研究方向。本文深入分析并总结了凝胶电解质应用于柔性超级电容器的独特优势及其关键性能优化的方法,包括：调控导电离子含量及传输路径以提高离子电导率;采用双重物理交联和模板化合成策略调节凝胶网络结构以改善机械性能;引入有机液体、离子液体等溶剂限制冰晶形成,从而拓宽工作温度范围。然而,凝胶电解质在柔性超级电容器应用中仍然面临一系列挑战,包括生物相容性不足、电极/电解质界面兼容性弱以及合成材料的环保性不佳。未来研究需进一步解决上述问题,以实现凝胶电解质在柔性超级电容器中的高效应用。