Poelchen Georg, Rusinov Igor P, Schulz Susanne, Güttler Monika, Mende Max, Generalov Alexander, Usachov Dmitry Yu, Danzenbächer Steffen, Hellwig Johannes, Peters Marius, Kliemt Kristin, Kucherenko Yuri, Antonov Victor N, Laubschat Clemens, Chulkov Evgueni V, Ernst Arthur, Kummer Kurt, Krellner Cornelius, Vyalikh Denis V
European Synchrotron Radiation Facility, 71 Avenue des Martyrs, 38043 Grenoble, France.
Institut für Festkörper- und Materialphysik, Technische Universität Dresden, 01062 Dresden, Germany.
ACS Nano. 2022 Mar 22;16(3):3573-3581. doi: 10.1021/acsnano.1c10705. Epub 2022 Feb 14.
The f-driven temperature scales at the surfaces of strongly correlated materials have increasingly come into the focus of research efforts. Here, we unveil the emergence of a two-dimensional Ce Kondo lattice, which couples ferromagnetically to the ordered Co lattice below the P-terminated surface of the antiferromagnet CeCoP. In its bulk, Ce is passive and behaves tetravalently. However, because of symmetry breaking and an effective magnetic field caused by an uncompensated ferromagnetic Co layer, the Ce 4f states become partially occupied and spin-polarized near the surface. The momentum-resolved photoemission measurements indicate a strong admixture of the Ce 4f states to the itinerant bands near the Fermi level including surface states that are split by exchange interaction with Co. The temperature-dependent measurements reveal strong changes of the 4f intensity at the Fermi level in accordance with the Kondo scenario. Our findings show how rich and diverse the f-driven properties can be at the surface of materials without f-physics in the bulk.
强关联材料表面的f驱动温度标度越来越成为研究工作的焦点。在此，我们揭示了二维铈近藤晶格的出现，它在反铁磁体CeCoP的P端表面以下与有序钴晶格铁磁耦合。在其体相中，铈是惰性的，表现为四价。然而，由于对称性破缺以及未补偿的铁磁钴层引起的有效磁场，铈4f态在表面附近变得部分占据且自旋极化。动量分辨光电子能谱测量表明，铈4f态与费米能级附近的巡游能带强烈混合，包括与钴交换相互作用分裂的表面态。温度相关测量揭示了费米能级处4f强度随近藤效应的变化。我们的研究结果表明，在体相中没有f物理的材料表面，f驱动的性质可以是多么丰富多样。
