Regensburg 2016 – wissenschaftliches Programm

Bereiche | Tage | Auswahl | Suche | Aktualisierungen | Downloads | Hilfe

MA: Fachverband Magnetismus

MA 33: Surface Magnetism II (jointly with O)

MA 33.2: Vortrag

Mittwoch, 9. März 2016, 15:15–15:30, H31

Collective magnetism in a hybrid magnetic-superconducting system: Co aggregates on Pb — •Jeison A. Fischer, Srijan S. Saha, Régis Decker, Michael Caminale, Hirofumi Oka, Dirk Sander, Valeri Stepaniuk, and Jürgen Kirschner — Max-Planck-Institut für Mikrostrukturphysik, Weinberg 2, 06120 Halle, Germany

Combining the quantum phenomena superconductivity and magnetism on the nanoscale opens the path towards the exploitation of new types of electronic excitations, such as Majorana end-states [1]. These phenomena rest on the presence of magnetism in nanoscale hybrid magnetic-superconducting systems. Here, we present a combined experimental low-temperature scanning tunneling spectroscopy (STS) and theoretical first-principles study, which surprisingly finds no evidence for a sizable magnetic moment in Co monomers on a Pb surface. When some ten Co atoms aggregate together, we observe by STS at 1.8 K the appearance of additional peaks in the superconducting gap at ± 1.8 meV. These intragap states are hallmarks of the interaction of magnetic moments with a superconductor. Ab initio calculations reveal that structural relaxation of the Co adatom towards the Pb is the physical origin behind the suppression of the magnetic moment of the adatom. The resulting strong hybridization between Co and Pb leads to a balanced spin-split density of states of Co. In contrast, the Co aggregate binds farther above Pb, and a strong inter-atomic interaction within the Co aggregate leads to a conserved magnetic moment.

[1] R. M. Lutchyn et al. Phys. Rev. Lett. 105, 077001 (2010); S. Nadj-Perge et al. Science 346, 602 (2014).