Tuning magnetic properties in nanostructures on different length scales

该项目的目的是通过实验和理论研究通过改变不同长度尺度的界面粗糙度来调整纳米结构磁性的可能性，这种可能性可以通过改变生长方式、退火或再磁化过程中化学和磁性团簇的自组织、人工横向结构的形成、氢的吸收和其他外部作用来实现。我们将研究金属表面亚单层复层的磁性行为。自旋分辨量子阱态的研究将允许我们用原子分辨来研究磁性特征。对于Heusler合金，我们将追踪退火诱导非晶膜中的自组织如何导致长程有序的形成和恢复系统的磁响应。在具有V间隔层的磁性纳米结构中，我们将研究可逆氢吸附对已经生长的样品的非共线磁性有序演变的影响。因此，在一个单一的方法中，将在不同的空间尺度上研究磁性的调谐。参与该项目的大学将使用纳米结构生长和电子束光刻的先进技术。对衬底和缓冲层进行特殊处理，改变温度状态，生长过程中的沉积比例，以及其他特殊发明，如氢辅助生长，将使纳米结构具有所需的界面结构。然后，使用BESSY和ILL的大型设施的互补实验方法将用于样品控制以及结构和磁性质的调查。理论描述将包括基于从头算和模型哈密顿方法的电子和磁性结构的自洽计算的外延生长建模。项目参与者开发的原始代码将用于计算复杂的、空间上非均匀的结构，考虑到外部局部磁场中可能存在的非共线磁排序。目的是在微观哈密顿方法中为流动电子提供纳米结构中再磁化过程的第一个原子尺度计算。因此，该项目将使合作项目团队能够使用先进的材料技术和理论方法来解决有关界面粗糙度，磁性及其在外部作用下演变的基本问题。

The aim of the project is the experimental and theoretical investigation of the possibility to tune magnetic properties of nanostructures via modification of interface roughness at different length scales which can be achieved by variation of growth regimes, self-organization of chemical and magnetic clusters during annealing or remagnetization process, formation of artificial lateral structures, hydrogen absorption and other external actions. We will investigate the onset of magnetic behavior in submonolayer overlayers on metal surface. Spin resolved study of quantum well states will allow us to investigate magnetic features with atomic resolution. For Heusler alloys we will trace how annealing induced self-organization in amorphous films can lead to the formation of long-range order and revive the magnetic response of the system. In magnetic nanostructures with V spacer layers we will investigate the influence of reversible hydrogen adsorption on the evolution of non-collinear magnetic ordering for already grown samples. Thus, tuning the magnetic properties will be studied at different spatial scales within a single approach. Advanced technologies for nanostructure growth and electron beam lithography will be used which are available at the Universities participating in the project. Special treatment of substrate and buffer layers, changing of temperature regime, deposition ratio during the growth, other special inventions, such as hydrogen assisted growth, will allow to make nanostructures with required interface structure. Than complimentary experimental methods with using of large scale facilities at BESSY and ILL will be applied for sample control as well as for the investigation of structural and magnetic properties. The theoretical description will include modelling of the epitaxial growth with self-consistent calculations of electronic and magnetic structures on the basis of ab initio and model Hamiltonian approaches. Original codes developed by project participants will be used for calculation of complex, spatially non-homogeneous structures taking into account possible non-collinear magnetic ordering in external local magnetic fields. The aim is to provide the first atomic scale calculations of remagnetization processes in nanostructures within a microscopic Hamiltonian approach for itinerant electrons. The project will thus enable the collaborating project team to use advanced material technology and theoretical approaches for addressing fundamental questions about interface roughness, magnetism and their evolution under external actions.