Correlation effects in self-organized atomic nanostructures on semiconductor surfaces

这个项目扩展了第一阶段致力于一维和二维关联电子系统的富有成效的研究，该系统是由金属原子在半导体表面亚单层区域自组织外延生长形成的。这种方法通过改变原子组成和掺杂，在很大范围内利用了电子性质的可调性。电子相互作用的作用通过角度分辨光电发射和扫描隧道光谱的组合进行了实验研究，目的是在低温下获得高分辨率的光谱特性。我们最近在Ge(001)上Au诱导的原子链中Tomonaga-Luttinger液体行为的发现为研究大量的量子现象开辟了一条新的实验途径。以幂定律行为为特征的电子光谱将被局部探测，以绘制在链端或故意散射中心的边界附近预期的重大变化。掺杂对电子关联的影响是可以直接观察到的，链间原子之间的桥联将导致“空间交叉”。利用在Si(111)和Ge(111)上的三角形表面晶格中含有大量重吸附原子(Sn，Pb，Au)的2D电子系统，实现了Mott-Hubbard绝缘体与受挫反铁磁序缠绕在一起。通过改变化学组成或覆盖率，可以实现不同的关联机制，从而触及某些系统中与超导电性的有趣竞争。电子关联的特征是通过k分辨光谱函数记录的，并将与包括磁相互作用的高级多体计算相关。此外，来自大原子的强自旋-轨道相互作用可以导致螺旋起伏的自旋织构，这将通过自旋分辨光电子能谱来解决，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.