ELFT HÍRADÓ

[Janos Asboth <asboth.janos AT ttk.bme.hu>]

Meghívó

BME Elméleti Fizika Szeminárium,

okt. 27. péntek 10h15,

1111 Budapest, Budafoki út 8., BME F III. magasföldszint 01.,
Elméleti Fizika Tanszék szemináriumi szoba

Rózsa Levente (Wigner FK):
Yu-Shiba-Rusinov states in spin chains 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 band structure of YSR states. In ferromagnetic chains the
spin-orbit coupling opens a minigap in the bands around the Fermi energy
where end states are formed, but the small size of this gap in typical
material platforms is found to lead to a long-range extension and
interactions between these precursors of Majorana bound states [1]. The
minigap is larger in antiferromagnetic chains where the spin-orbit coupling
is not necessary for its formation, but the well-localized end states in
this minigap typically have a topologically trivial origin [2]. The
theoretical concepts are illustrated by experimental realizations in
specific materials.

[1] L. Schneider, P. Beck, J. Neuhaus-Steinmetz, L. Rózsa, T. Posske, J.
Wiebe, and R. Wiesendanger, Nat. Nanotechnol. 17, 384 (2022).
[2] L. Schneider, P. Beck, L. Rózsa, T. Posske, J. Wiebe, and R.
Wiesendanger, Nat. Commun. 14, 2742 (2023).

Minden érdeklődőt szeretettel várunk.
Asbóth János,
 szemináriumi koordinátor