Université de Strasbourg, CNRS, IPCMS UMR 7504, F-67034 Strasbourg, France.
Karlsruher Institut für Technologie, Institut für Nanotechnologie, D-76344 Eggenstein-Leopoldshafen, Germany.
Nanoscale. 2019 Nov 28;11(44):21167-21179. doi: 10.1039/c9nr05873g. Epub 2019 Oct 30.
Bis(phthalocyaninato)lanthanide (LnPc) double-decker-based devices have recently attracted a great deal of interest for data encoding purposes. Although the 4f-electrons of lanthanide ions play a key role in the experimental methodology, their localized character, deeper in energy compared to the 3d electrons of transition metals, hampers a detailed investigation. Here, our approach consists of the follow-up of the entanglement process with other molecules and with the substrate electrons by means of space-resolved detection of the Kondo resonance by scanning tunneling spectroscopy (STS), using different substrates (from weak to strong interaction). It is found that TbPc molecules firstly interact with their environment by means of the π-radicals of the ligand. The radical spin of TbPc can be identified by STS on a weakly interacting substrate such as Au(111). In the case of a Ag(111) substrate, we are able to analyze the effect of an electron transfer on the molecule (pairing-up of the radical spin) and the subsequent quenching of the Kondo resonance. Finally, on a strongly interacting substrate such as Cu(111), a significant rearrangement of electrons takes place and the Kondo screening of the 4f electrons of the Tb ion of TbPc is observed. By comparative STS measurements on YPc, that has empty 4d and 4f shells, we prove that the Kondo resonance measured in the center of the TbPc molecule indeed stems from the 4f-electrons. At the same time, we provide evidence for the hybridization of the 4f states with the π electron.
双酞菁镧系（LnPc）双层基器件最近因其在数据编码方面的应用而引起了极大的关注。尽管镧系离子的 4f 电子在实验方法中起着关键作用，但由于它们的局域性质，能量比过渡金属的 3d 电子更深，这阻碍了对其的详细研究。在这里，我们的方法包括通过扫描隧道光谱学（STS）以空间分辨的方式来跟踪与其他分子和与基底电子的纠缠过程，使用不同的基底（从弱相互作用到强相互作用）。结果表明，TbPc 分子首先通过配体的π自由基与环境相互作用。TbPc 的自由基自旋可以通过 STS 在弱相互作用的基底（如 Au(111)）上识别。在 Ag(111)基底的情况下，我们能够分析电子转移对分子的影响（自由基自旋的配对）以及随后对 Kondo 共振的猝灭。最后，在强相互作用的基底（如 Cu(111)）上，电子发生了显著的重排，并且观察到 TbPc 中 Tb 离子的 4f 电子的 Kondo 屏蔽。通过对具有空的 4d 和 4f 壳层的 YPc 的比较 STS 测量，我们证明了在 TbPc 分子中心测量的 Kondo 共振确实来自 4f 电子。同时，我们为 4f 态与π电子的杂化提供了证据。
