Levente Rózsa
Wigner Research Centre for Physics, Budapest
Yu-Shiba-Rusinov states in (anti)ferromagnetic
spin structures on superconductors
Magnetic impurities in conventional superconductors locally break Cooper pairs, leading to the emergence of Yu-Shiba-Rusinov (YSR) bound states. Chains of YSR impurities have been theoretically predicted to give rise to Majorana bound states, which hold promises for realizing topological quantum computers. A fundamental understanding of the formation of YSR states in small atomic clusters is essential for revealing the topological properties of the YSR band structure. The accurate theoretical modelling of YSR states represents a considerable challenge, since it requires a simultaneous description of the electronic structure, the magnetic ordering of the impurities and superconductivity on significantly different energy scales. Here, first-principles simulations are combined with tight-binding model calculations to determine the influence of the electronic and magnetic structure on the interactions between the YSR states. It is explained how the spin-orbit coupling influences the hybridization of YSR bound states in dimers with ferromagnetic and antiferromagnetic spin alignments [1]. The calculations are extended to atomic chains, where extended and interacting precursors of Majorana bound states are found in ferromagnetic chains [2], while localized but topologically trivial end states are formed in antiferromagnetic chains [3]. The theoretical concepts are illustrated by experimental realizations in specific materials.
References:
[1] P. Beck, L. Schneider, L. Rozsa, K. Palotas, A. Laszloffy, L. Szunyogh, J. Wiebe, and R. Wiesendanger, Nat. Commun. 12, 2040 (2021).
[2] L. Schneider, P. Beck, J. Neuhaus-Steinmetz, L. Rozsa, T. Posske, J. Wiebe, and R. Wiesendanger, Nat. Nanotechnol. 17, 384 (2022).
[3] L. Schneider, P. Beck, L. Rozsa, T. Posske, J. Wiebe, and R. Wiesendanger, arXiv:2211.00561(2022).