Electronic theory of magnetic domain walls and magnetic field switching in transition-metal nanowires: Confinement, local environment and temperature effects

磁畴和畴壁（DW）是任何铁磁材料的重要特征。了解磁性纳米结构中DW的性质对于技术应用至关重要，特别是在存储器和自旋电子器件中，DW的存在不能与存储的信息本身分离。该项目的目标是过渡金属磁性纳米线（NW）中DW的物理学和相关磁化重取向转变的量子力学理论描述。关注的焦点是DW的形成能量和尺寸，壁内磁序的性质，两个壁之间的相互作用，磁场的影响和磁化翻转的机制。这些属性的宽度，结构，组合物和温度的函数进行了研究，其目的是将它们与线特定的电子结构和与环境相关的各向异性能量和局部时刻之间的有效交换耦合。详细研究了线-衬底相互作用的影响，特别是对于具有较强自旋-轨道耦合的高度可极化衬底（例如，Pd、Pt和Rh）。除了量子力学的理解DWs在CNONWs，这项工作应该提供电子理论和唯象微磁方法之间的联系，应该导致一个基于显微镜的多尺度建模的一维纳米结构。

Magnetic domains and domain walls (DWs) are an important feature of any ferromagnetic material. Understanding the properties of DWs in magnetic nanostructures is crucial to technological applications, particularly in memory and spin-electronic devices where the presence of a DW cannot be disjoined from the stored information itself. The goal of this project is the quantum-mechanical theoretical description of the physics of DWs in transition-metal magnetic nanowires (NWs) and of the associated magnetization reorientation transitions. The focus of attention are the formation energy and size of the DWs, the nature of the magnetic order within the wall, the interactions between two walls, the effect of magnetic fields and the mechanisms for magnetization switching. These properties are investigated as a function of width, structure, composition and temperature with the aim of correlating them with the wire-specific electronic structure and with the environment-dependent anisotropy energies and effective exchange couplings between local moments. The effects of wire-substrate interactions are investigated in detail, in particular for highly-polarizable substrates with stronger spin-orbit couplings (e.g., Pd, Pt and Rh). Besides the quantum mechanical understanding of DWs in ultrathin NWs, this work should provide a link between electronic theory and phenomenological micromagnetic approaches that should lead to a microscopically-based multiscale modeling of 1D nanostructures.