Quasi-particle interference in surface- and bulk-doped topological insulators and Weyl semimetals

表面和体掺杂拓扑绝缘体和韦尔半金属中的准粒子干涉

• 批准号: 237559088
• 负责人: Professor Dr. Matthias Bode
• 金额: --
• 依托单位: Lehrstuhl für Experimentelle Physik II
• 依托单位国家: 德国
• 项目类别: Priority Programmes
• 财政年份: 2013
• 资助国家: 德国
• 起止时间: 2012-12-31 至 2020-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/237559088?language=en
• 关键词: Quasi; particle; interference; surface; bulk

Topological insulators are characterized by massless Dirac fermions which are topologically protected and exhibit a helical spin structure due to spin-orbit coupling. These unique electronic properties make them promising candidates for future spintronics applications. However, a detailed understanding of the correlation between the spin-resolved band structure, scattering events, and specific transport properties is still due. In this project we will continue our investigations of magnetically doped topological insulators. By spin-polarized scanning tunneling microscopy (STM) and spectroscopy (STS) we will study the mechanisms that establish long-range magnetic order between surface dopants mediated by topological states. Furthermore, we will perform XMCD and temperature-dependent scanning probe experiments on bulk-doped crystals to better understand the electronic structure of magnetically ordered TIs exhibiting the quantum anomalous Hall effect. We will pursue our investigations of hybrid organic-TI interfaces. This novel route, which we dis- covered during the first funding period, holds the promise of magnetically doping and potentially even gating TI surfaces by means of self-assembled molecular layers. We will continue our quasiparticle interference (QPI) and STS experiments to study to what extent the presence of a molecular overlayer modifies the electronic properties of the TI surface state. The potential for magnetically ordered molecular superstructures, one of the milestones towards spintronics applications, will be scrutinized by XMCD and spin-resolved STM experiments. In cooperation with collaborators from MPIs at Dresden (Yan, Felser) and Halle (Parkin) we will study the (spin-resolved) electronic properties of Weyl semimetals which exhibit pairs of Weyl points which carry topological monopoles of quantized Berry flux in momentum space. We will not only study the scattering states of theses surfaces in real space, but also investigate how local tunneling spectra and the QPI pattern change once Weyl semimetal surfaces are magnetically doped.

拓扑绝缘体的特征是无质量的狄拉克费米子，它们受到拓扑保护，由于自旋-轨道耦合而表现出螺旋自旋结构。这些独特的电子特性使它们成为未来自旋电子学应用的有希望的候选者。然而，对自旋分辨能带结构、散射事件和特定输运性质之间的关系的详细了解仍有待进一步研究。在本项目中，我们将继续研究磁掺杂拓扑绝缘体。通过自旋极化扫描隧道显微镜（STM）和光谱学（STS），我们将研究由拓扑态介导的表面掺杂剂之间建立远程磁序的机制。此外，我们将在块体掺杂晶体上进行XMCD和温度相关扫描探针实验，以更好地了解具有量子反常霍尔效应的磁有序ti的电子结构。我们将继续我们的杂化有机ti界面的研究。我们在第一个资助期内发现的这种新途径有望通过自组装分子层实现磁掺杂和潜在的均匀门控TI表面。我们将继续进行准粒子干涉（QPI）和STS实验，以研究分子覆盖层的存在在多大程度上改变了TI表面态的电子特性。磁有序分子超结构的潜力是自旋电子学应用的里程碑之一，将通过XMCD和自旋分辨STM实验进行仔细研究。与来自德累斯顿（Yan, Felser）和哈雷（Parkin）的mpi合作者合作，我们将研究Weyl半金属的（自旋分辨）电子特性，这些半金属在动量空间中表现出携带量子化Berry通量拓扑单极子的Weyl点对。我们不仅将研究这些表面在实际空间中的散射状态，还将研究在Weyl半金属表面被磁掺杂后，局部隧道光谱和QPI图是如何变化的。