Spin phenomena in 2D materials – highly anisotropic magnets at the monolayer limit

单层范德华材料在二维（2D）中具有强键，在第三维（2D）中具有弱键，这使得研究人员成为以前未观察到的物理现象（如高迁移率狄拉克电子）的宿主，并且由于它们在设备中具有原子薄电子元件的潜力。然而，对二维化合物的集体磁性的研究直到最近才开始，尽管它们可能导致基于二维铁磁体和拓扑绝缘体堆叠的低损耗传导，或者在原子极限下基于自旋的计算。一个抑制因素是可用于实验研究的化合物的稀疏性，目前仅限于铁磁绝缘体CrI3和Cr2Ge2Te6。后一种化合物的磁性远远低于液氮温度（< -196°C）。在这里，我建议合成一个过渡金属基金属间化合物和簇状范德华化合物及其单层化合物库。为了实现这些单层，我将应用固态化学技术来调整磁性，并减少抑制范德华层分离的缺陷的数量。第一组合成将专注于制造金属铁磁单层化合物，这种化合物在液氮温度以上，甚至可能在室温以上都具有磁性。在第二组实验中，我将研究如何通过减少每个堆栈的层数来平衡自旋的共向和反向。这些微妙的相互作用可能会产生令人沮丧的磁铁，其特征是局部尺度上的磁相互作用，但没有长期的磁秩序。创造具有金属铁磁性或受挫磁性行为的单层化合物是纳米尺度上凝聚态物质实验的平台，也是基于自旋和量子计算的原子薄构建块。

Single layered van der Waals materials with strong bonding in two dimensions (2D) and weak bonds in the third have galvanized researchers as hosts for previously unobserved physical phenomena such as high mobility Dirac electrons and due to their potential for atomically thin electronic components in devices. Yet, investigations into collective magnetism in 2D compounds only started recently, though they could lead to loss less conduction based on a stack of a 2D ferromagnet and a topological insulator or to spin based computation at the atomic limit. One inhibiting factor is the sparsity of compounds available for experimental studies, which at the moment are restricted to the ferromagnetic insulators CrI3 and Cr2Ge2Te6. The magnetic properties of the latter compounds appear far below liquid nitrogen temperatures (< -196 °C). Here, I propose to synthesize a library of transition metal based intermetallic and cluster van der Waals compounds as well as their monolayers. To achieve these monolayers, I will apply techniques of solid state chemistry to tune the magnetic properties as well as reduce the number of defects which inhibit the separation of the van der Waals layers. The first set of syntheses will focus on creating metallic ferromagnetic monolayer compounds which are magnetic above the temperature of liquid nitrogen, possibly even room temperature. In a second set of experiments, I will investigate how to balance the co- and anti-alignment of spins by reducing the numbers of layer per stack. These subtle interaction could create frustrated magnets which features magnetic interactions on the local scale, but without long range magnetic order. The creation of monolayer compounds exhibiting metallic ferromagnetism or frustrated magnetic behavior are of interest as platforms for condensed matter experiments on the nanoscale and as atomically thin building blocks in spin based and quantum computation.