Computational design of spin-caloric nanosructures

现代信息技术在很大程度上是以纳米级的磁性系统为基础的。信息存储在磁性纳米结构中，这些结构驻留在硬盘或磁性存储器中。这些信息通过自旋极化电流读出，在许多情况下写入，即带有磁化的电流。这些电流不可避免地促进热量的产生和传递，用术语“热效应”来概括。相反的现象，即由于温度梯度的强迫热流产生自旋极化的电子电流，也是不可避免的。因此，我们在这些系统中面临电荷、自旋和热流之间的耦合。这种现象在很大程度上取决于材料的类型，但由于量子约束效应，它们也取决于纳米结构的大小和几何形状。这基本上是由电子在纳米结构边界的反射引起的，并且对系统量子水平的密度有重要影响。本文提出了纳米结构系统中电荷、自旋和热流耦合的理论和计算研究，分析并可能优化材料类型和结构参数的影响。这项研究将采用最先进的量子力学方法进行。我们预计，在资助期结束时，我们将了解如何将纳米结构的自旋热输运特性调整到应用所需的值。

Modern information technology is based to a great extent on nanometer-sized magnetic systems. Information is stored in magnetic nanostructures that reside on hard disks or in magnetic memories. This information is read-out, and in many cases written-in, by spin-polarized currents, i.e., electrical currents carrying a magnetization. These currents inevitably contribute to heat production and heat transport, summarized with the term “caloric effects.” The inverse phenomenon, i.e. the creation of a spin-polarized electron current due to a heat current that is forced by a temperature gradient, is inevitable as well. We therefore face a coupling between the charge, spin, and heat current in these systems. Such phenomena depend strongly on the type of material, but they also depend on the nanostructure size and geometry because of an effect known as quantum confinement. This is basically caused by the reflection of electrons at the nanostructure boundaries and crucially affects the density of quantum levels of the system. Here we propose a theoretical and computational study of the coupling of charge, spin and heat currents in nanostructured systems, analyzing and possibly optimizing the influence of material type and structure parameters. The study will take place with state-of-the-art quantummechanical methods. We anticipate that at the end of the funding period we will understand how to tune the spin-caloric transport properties of nanostructures to values that are desired for application.