Speaker
Jens Paaske
Description
In this talk I show how a chain of magnetic moments
exchange coupled to a conventional three-dimensional
superconductor is unstable towards the formation of a
magnetic spiral state. Beyond weak exchange coupling the
spiral wave vector greatly exceeds the inverse
superconducting coherence length as a result of the strong
spin-spin interaction mediated through the subgap band of
Yu-Shiba-Rusinov states. Moreover, the simple spin-spin
exchange description breaks down as the subgap band
crosses the Fermi energy, wherein the spiral phase becomes
stabilized by the spontaneous opening of a p-wave
superconducting gap within the band. This leads to the
possibility of electron-driven topological superconductivity
with Majorana boundary modes using magnetic atoms on
superconducting surfaces.
