Seminarium Fizyki Materii Skondensowanej

It is known that a chain of magnetic moments deposited on a bulk superconductor self-organizes into a helical structure. The ordering is driven by an effective RKKY-type interaction that is mediated by itinerant electrons. It is interesting that for wide range of system parameters the wave vector characterizing the helix self-tunes to support a topological state with Majorana edge modes. This feature has been demonstrated in the ground state, also in the presence of some forms of disorder. In this work we study the stability of this self-organized topological state at finite temperatures. We show how the correlation length of the spiral order decreases with increasing temperature. In most cases the destruction of the helical order drives the system into a topologically trivial state. For some parameters, however, the topological state survives up to very high temperatures despite the absence of the helical order.