Coherent long-range magnetic bound states in a superconductor

Gerbold C. S Ménard (1) , Sébastien S Guissart (2) , Christophe S Brun (1) , Stéphane V Pons (3, 1) , Vasily V Stolyarov (4, 1) , François Debontridder (1) , Matthieu V Leclerc (1) , Etienne Janod (5) , Laurent S Cario (5) , Dimitri V Roditchev (3, 1) , Pascal S Simon (2) , Tristan S Cren (1)

1 INSP-E2 - Spectroscopie des nouveaux états quantiques
2 LPS - Laboratoire de Physique des Solides
3 LPEM - Laboratoire de Physique et d'Etude des Matériaux (UMR 8213)
4 MIPT - Moscow Institute of Physics and Technology [Moscow]
5 IMN - Institut des Matériaux Jean Rouxel

The quantum coupling of fully different degrees of freedom is a challenging path towards new functionalities for quantum electronics [1–3]. Here we show that the localized classical spin of a magnetic atom immersed in a superconductor with a two-dimensional electronic band structure gives rise to a long range coherent magnetic quantum state. We experimentally evidence coherent bound states with spatially oscillating particle-hole asymmetry extending tens of nanometers from individual iron atoms embedded in a 2H-NbSe 2 crystal. We theoretically elucidate how reduced dimensionality enhances the spatial extent of these bound states and describe their energy and spatial structure. These spatially extended magnetic states could be used as building blocks for coupling coherently distant magnetic atoms in new topological superconducting phases [4–11].

Domaines: Supraconductivité [cond-mat.supr-con]

Gerbold C. S Ménard, Sébastien S Guissart, Christophe S Brun, Stéphane V Pons, Vasily V Stolyarov, et al.. Coherent long-range magnetic bound states in a superconductor. Nature Physics, 2015, 11, pp.1013 - 1016. ⟨10.1038/nphys3508⟩. ⟨hal-01387239⟩