Synthesis, Assembly, and Optical and Transport Studies of Magnetic Nanostructures

9871849 Metiu我们计划合成和组装稀磁半导体纳米结构，并利用近场光学显微镜研究其输运和光学性质。众所周知，通过减小半导体结构的尺寸，我们可以影响和控制其中电子的性质。我们对这种尺寸缩小如何影响这些系统的磁性几乎一无所知，尽管我们预计这些影响将是相当大的。我们将制备掺杂具有磁性的二价过渡金属离子(Mn(II)、Cr(II)、Fe(II)和Cu(II))的II-VI半导体纳米晶点。因此，我们可以研究限制对这些材料的交换作用和磁光性质的影响。我们计划使用近场显微镜对单个点的磁光特性进行飞秒和连续波研究，并确定这些特性如何依赖于点的大小。我们还计划创建这样的点的集合，这样我们就可以研究这些点之间的相互作用所产生的集体效应。我们最重要的工具之一是近场光学显微镜。这是一个很棒的工具，有许多令人兴奋的用途，但由于缺乏正在研究的结构中产生的电磁场的定量理论，对测量结果的定量解释受到了阻碍。我们建议发展新的理论方法来解决这个问题。这里提出的那种研究的动机是制造更小的电子设备和更密集的计算机存储器的需求。随着这些器件的元素变得更小，其中电子的性质也在改变。如果我们不能预测和理解其中的电子将如何行为，我们就无法设计这些器件。我们的工作希望填补我们理解上的这一空白。最终的计算机将是一种电子本身是计算元件的设备。目前的主要候选者是各种自旋态被激发的系统，因为它们保持给予它们的信息(相干性)的时间最长。这也是为什么研究小型结构中的自旋行为可能会影响未来技术的另一个原因。该奖项由多学科活动办公室、数学和物理科学局材料研究司和工程局电气和通信系统司支持。

9871849 Metiu We plan to synthesize and assemble dilute magnetic semiconductor nanostructures and study their transport and optical properties by using near field optical microscopy. It is well known that by reducing the size of a semiconductor structure we can affect and control the properties of the electrons in it. We know practically nothing about the way in which this size reduction affects the magnetic properties of these systems, even though we expect these effects to be considerable. We will prepare nanocrystalline "dots" of II-VI semiconductor doped with divalent transition metal ions with magnetic properties (Mn(II), Cr(II), Fe(II) and Cu(II) ). We can thus study the effect of confinement on the exchange interactions and the magneto-optical properties of these materials. We plan to use a near field microscope to perform femtosecond and cw studies of the magneto-optical properties of individual dots and to determine how these properties depend on dot sizes. We also plan to create ensembles of such dots so that we can study the collective effects created by the interaction between the dots. One of our most important tools is the near field optical microscope. This is a wonderful tool with many exciting uses, but the quantitative interpretation of the measurements is hampered by the lack of a quantitative theory of the electromagnetic fields produced in the structure being studied. We propose to develop new theoretical methods for solving this problem. %%% The kind of studies proposed here are motivated by the need of making smaller electronic devices and denser computer memories. As the elements of these devices become smaller the properties of the electrons in them are being modified. We cannot design these devices if we cannot anticipate and understand how the electrons in them will behave. Our work hopes to fill this gap in our understanding. The ultimate computer will be a device in which the electrons themselves are computing elements. The main candidates right now are systems in which various spin states are being excited, since they maintain the information imparted to them (coherence) for the longest time. This is one additional reason why the study of spin behavior in small structures may impact future technologies. This award is being supported by the Office of Multidisciplinary Activities; the Division of Materials Research, Directorate for Mathematical and Physical Sciences; and the Division of Electrical and Communications Systems, Directorate for Engineering.***