Magnetic excitations of single atoms and molecules on superconductors probed by scanning tunneling spectroscoppy

通过扫描隧道光谱探测超导体上单个原子和分子的磁激发

• 批准号: 240641355
• 负责人: Professorin Dr. Katharina Franke
• 金额: --
• 依托单位: Institut für Experimentalphysik
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2013
• 资助国家: 德国
• 起止时间: 2012-12-31 至 2016-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/240641355?language=en
• 关键词: Magnetic; excitations; single; atoms; molecules

In the framework of this proposal we will resolve the basic interaction mechanisms of atomic and molecular spins with a superconducting substrate at the atomic scale. The magnetic moment of the adsorbates couples via exchange interaction to the conduction electrons and Cooper pairs of the substrate. On the one hand, this leads to the screening of the magnetic moment via the so-called Kondo effect and, on the other hand, to a change in the pairing energy of the Cooper pairs, which is reflected in Shiba states inside the superconducting energy gap. The competition of these processes yields a complex many-body state, which we will resolve using scanning tunneling spectroscopy. In a previous work, we could experimentally demonstrate a universal correlation between the efficiency of Kondo screening and the energy of Shiba states in spin-1/2 systems, which has been predicted by theory decades ago. With these results, it also became evident that tiny differences in the atomic environment critically influence the resulting magnetic ground state. We will now increase the complexity of the spin systems and of their environment in order to integrate further factors into the picture of competing interactions. In particular, it is the goal to understand, how higher spin states of the adsorbates (S>1/2), magnetic anisotropy or exchange interactions to nearest neighbors influence the magnetic ground state and excited states. This understanding is not only of fundamental interest, but also important for realizing magnetic nanostructures for spintronic devices.

在该提案的框架内，我们将在原子尺度上解决原子和分子自旋与超导基底的基本相互作用机制。吸附物的磁矩通过交换相互作用与基底的传导电子和库珀对耦合。一方面，这导致通过所谓的近藤效应屏蔽磁矩，另一方面，导致库珀对的配对能量发生变化，这反映在超导能隙内的芝态中。这些过程的竞争产生了复杂的多体态，我们将使用扫描隧道光谱来解决这个问题。在之前的工作中，我们可以通过实验证明近藤屏蔽效率与自旋1/2系统中芝态能量之间的普遍相关性，这在几十年前就已经被理论预测到了。通过这些结果，还可以明显看出原子环境中的微小差异会严重影响最终的磁性基态。我们现在将增加自旋系统及其环境的复杂性，以便将更多因素整合到竞争相互作用的图中。特别是，我们的目标是了解吸附物的较高自旋态 (S>1/2)、磁各向异性或与最近邻居的交换相互作用如何影响磁性基态和激发态。这种理解不仅具有根本意义，而且对于实现自旋电子器件的磁性纳米结构也很重要。