Correlation effects in self-organized atomic nanostructures on semiconductor surfaces

该项目扩展了第一阶段致力于一维和二维相关电子系统的生产性研究，这些系统是由半导体表面亚单层状态下金属原子的自组织外延生长形成的。这种方法通过原子成分的变化和掺杂来利用电子性质在大范围内的可调性。电子相互作用的作用通过角分辨光电发射和扫描隧道光谱的结合实验来解决，旨在达到低温度下光谱特性的高分辨率。我们最近在Ge（001）上发现了au诱导原子链中的Tomonaga-Luttinger液体行为，为研究丰富的量子现象开辟了一条新的实验途径。以幂律行为为特征的电子光谱将在局部进行探测，以绘制在链端边界附近或故意散射中心附近预期的重大变化。掺杂对电子相关性的影响可以直接观察到，并且链之间的桥接原子将有助于诱导“维度交叉”。在Si（111）和Ge（111）的三角形表面晶格中，含有重原子（Sn, Pb, Au）的丰富的二维电子系统被用来实现莫特-哈巴德绝缘体与受挫的反铁磁序交织在一起。通过改变化学成分或覆盖范围，可以实现不同的相关机制，从而触及某些系统中与超导性的迷人竞争。电子相关的特征是通过k分辨谱函数记录的，并将与包括磁相互作用在内的高级多体计算相关。此外，源自大原子的强自旋轨道相互作用可以导致螺旋波动的自旋结构，这可以通过自旋分辨光发射来解决，这与拓扑绝缘体中的现象非常相似。

This project extends the productive investigations of the first period devoted to one- and two dimensional correlated electron systems, which are formed by self-organized epitaxial growth of metal atoms in the submonolayer regime on semiconductors surfaces. This approach exploits the tunability of the electronic properties over a wide range by variation of the atomic constituents and by doping. The role of the electron interactions is addressed experimentally by a combination of angle-resolved photoemission and scanning tunneling spectroscopy, aiming at high resolution of the spectral properties down to low temperatures. Our recent discovery of Tomonaga-Luttinger liquid behavior in atomic Au-induced chains on Ge(001) has opened a novel experimental pathway to study a wealth of quantum phenomena. The electronic spectra, characterized by a power-law behavior, will be probed locally to map the significant modifications expected in the vicinity of boundaries at chain ends or by intentional scattering centers. The effect of doping on the electron correlations can be witnessed directly, and bridging atoms between chains will serve to induce a “dimensional crossover”. The rich variety of 2D electron systems with heavy adatoms (Sn, Pb, Au) in a triangular surface lattice on Si(111) and Ge(111) is used to realize Mott-Hubbard insulators intertwined with frustrated antiferromagnetic order. Different correlation regimes can be realized by changing the chemical composition or the coverage, thereby touching the fascinating competition with superconductivity in some of the systems. The signatures of electron correlation are recorded via the k-resolved spectral function, and will be related to advanced many-body calculations that include magnetic interactions. Moreover, strong spin-orbit interactions originating from the large atoms can lead to helical undulating spin textures, to be addressed by spin-resolved photoemission, which bear close resemblance to phenomena in topological insulators.