Condensed Matter Physics Seminar

Most physical systems known to date tend to resist entering the topological phase and must be fine tuned to reach the latter. In this talk I will introduce a system in which a key dynamical parameter adjusts itself in response to the changing external conditions so that the ground state naturally favors the topological phase. The system consists of a quantum wire formed of individual magnetic atoms placed on the surface of an ordinary s-wave superconductor. It realizes the Kitaev paradigm of topological superconductivity when the wavevector characterizing the emergent spin helix dynamically self-tunes to support the topological phase. We call this phenomenon self-organized topological state. Recent measurements in the Yazdani group show possible signatures of this phenomenon in chains of Gd atoms assembled on 110 surfaces of lead.