Many-body effects in the electronic structure and the superconductivity of adsorbates on semiconductor surfaces

电子结构中的多体效应和半导体表面吸附物的超导性

• 批准号: 155997461
• 负责人: Professor Dr. Werner Hanke
• 金额: --
• 依托单位: Institut für Theoretische Physik und Astrophysik
• 依托单位国家: 德国
• 项目类别: Research Units
• 财政年份: 2009
• 资助国家: 德国
• 起止时间: 2008-12-31 至 2016-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/155997461?language=en
• 关键词: Many; body; effects; electronic; structure

This project continues and extends our study of many-body effects in the electronic structure and emerging phases of adsorbates on semiconductor surfaces. The variation of coverage/ doping allows for a controlled study of electronic correlations beyond traditional band theory in competition with geometrical frustration (triangular lattice). In the first period, on the basis of progress in methodology (LDA + Variational Cluster Approaches, LDA + DMFT, QMC, Functional Renormalization Group), we concentrated on the Mott transition and predicted the underlying geometrical and emerging magnetic orders in specific adatomic systems. In close collaboration with project P1, the fingerprints of this magnetic order were identified in spectroscopies, such as the corresponding photoemission spectra. In the continuation, we would like to (i) address possible spin-liquid phases and (ii) systematically extend our studies to superconductivity such as the recently detected superconductivity in the Pb(In) on Si(111). Here, questions of general interest are the fragile nature of a possible 2D superconducting state, susceptible to strong quantum-phase fluctuations and the glue for Cooper-pairing. Furthermore, we concentrate on (iii) the role of spin-orbit coupling and (iv) new paths to unconventional topological superconductivity (SC). Part (iii) is motivated from our findings (with P1) for the Au/Ge system with its strong-spin orbit coupling, where a striking similarity was detected to the surface Dirac state of the topological insulator Bi2Te3. In Part (iv), we focus on chiral SC with a complex pairing gap and time-reversal symmetry breaking. This non-trivial topology has an exceptionally rich phenomenology such as a quantum-spin and thermal Hall conductance as well as edge currents, which, together with the complex pairing gap, can be searched for in experiments. Last but not least, we want to study the combination of strong spin-orbit coupling and SC, and investigate whether the exciting possibility of pairing (singlet + triplet) mixing can be realized in adatom systems.

这个项目继续和扩展了我们对半导体表面吸附的电子结构和新出现的相的多体效应的研究。覆盖/掺杂的变化允许在几何受挫(三角形晶格)竞争中对电子关联进行受控研究，而不是传统的能带理论。在第一阶段中，我们在方法学(LDA+变分簇法、LDA+DMFT、QMC、泛函重整化群)的基础上，集中研究了Mott相变，并预测了具体原子系统的基本几何磁序和新出现的磁序。在与P1项目的密切合作下，在光谱学中确定了这种磁序的指纹，例如相应的光电子能谱。在接下来的文章中，我们希望(I)讨论可能的自旋-液体相，(Ii)系统地扩展我们的研究到超导电性，例如最近在Si(111)上的铅(In)中检测到的超导电性。在这里，普遍感兴趣的问题是可能的2D超导态的脆弱性质，容易受到强烈的量子相位波动的影响，以及库珀配对的粘合剂。此外，我们还集中讨论了(Iii)自旋-轨道耦合的作用和(Iv)非传统拓扑超导(SC)的新途径。第三部分是对具有强自旋轨道耦合的Au/Ge系统的研究结果(与P1)，其中发现与拓扑绝缘体Bi2Te3的表面Dirac态有惊人的相似之处。在第四部分中，我们重点研究了具有复杂配对能隙和时间反转对称性破缺的手性SC。这种非平凡的拓扑具有异常丰富的现象学，例如量子自旋和热霍尔电导以及边缘电流，这些都可以在实验中找到，再加上复杂的配对能隙。最后但并非最不重要的一点是，我们想要研究强自旋-轨道耦合与Sc的结合，并研究在吸附原子系统中能否实现配对(单态+三态)混合的激发可能性。