Andreev reflection spectroscopy of magnetic impurities on superconductors at the single-atom level

用扫描隧道显微镜研究单原子和单分子接触中的安德烈夫反射。利用实验方法的优点，即选择电极材料（尖端和单晶表面）的灵活性以及接触的原子精确表征，探索Andreev反射对超导体相相干长度的潜在依赖关系。此外，将利用扫描隧道显微镜形成的单原子和单分子接触，转移并建立基于Andreev反射的由磁性电极和超导电极组成的宏观点接触中电流的自旋极化分析。利用超导尖端和样品，以及吸附在尖端或样品表面的磁性杂质，计划揭示Andreev反射、Yu-Shiba-Rusinov态与磁性原子和分子与电极的杂化之间的关系。

The Andreev reflection will be studied in single-atom and singlemolecule contacts with a scanning tunnelling microscope. By exploiting the advantages of the experimental method, namely the flexibility in choosing the electrode materials – tip and singlecrystalline surface – as well as the atomically precise characterization of the contact, the potential dependence of Andreev reflection on the phase coherence length of the superconductor will be explored. Moreover, the analysis of the spin polarization of the current on the basis of Andreev reflection in macroscopic point contacts comprising magnetic and superconducting electrodes will be transferred and established for single-atom and single-molecule contacts formed with a scanning tunnelling microscope. The use of superconducting tips and samples as well as magnetic impurities adsorbed on either the tip or the sample surface is planned to unveil the relation between Andreev reflection, Yu-Shiba-Rusinov states and the hybridization of the magnetic atoms and molecules with the electrodes.