ELFT HÍRADÓ

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

Meghívó

BME Elméleti Fizika Szeminárium,

nov. 11. péntek 10h15,

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

Nyári Bendegúz (BME TTK Elméleti Fizika Tanszék):
From Yu-Shiba-Rusinov states to Majorana zero modes

The Majorana fermion was originally proposed by Ettore Majorana in 1937 as
an elementary particle which is its own antiparticle. Although this
elementary particle has not yet been detected, its analogons, Majorana
states (and Majorana Zero Modes, often called Majoranas) can appear as
quasiparticle excitations in condensed matter physics. These latter
have promising applications as building blocks of topological quantum bits,
based on their non-Abelian anyonic exchange statistics. Thanks to the rapid
development in scanning-tunneling microscopy techniques, today it is
possible to build the systems used in model calculations that should host
Majoranas, and measure their spectral properties. It remains challenging to
prove the presence of Majoranas from the data, and ab initio calculations
can help arrive at definite conclusions.

I will present an overview of our ab initio based results on the formation
of Majorana zero modes. I will start from a single magnetic impurity on the
surface of an s-wave superconductor,  introduce the Yu-Shiba-Rusinov
states, and then move on to magnetic chains. For some spin-spiral
configurations we found an induced minigap, which has zero energy states
localized to the ends of the chain in a spin triplet (superconducting)
state. By varying the spiraling angle we observed a phase transition to
another gapped state without zero energy states, which we expect to be a
topological phase transition.

Minden érdeklődőt szeretettel várunk.
Asbóth János,
 szemináriumi koordinátor