Majorana fermion chain at the Quantum Spin Hall edge

Understand

We study a realization of a 1d chain of Majorana bound states at the interfaces between alternating ferromagnetic and superconducting regions at a quantum spin Hall insulator edge.

• In the limit of well separated Majoranas, the system can be mapped to the transverse field Ising model.
• The disordered critical point can be reached by tuning the relative magnitude or phases of the ferromagnetic and superconducting order parameters.
• We compute the voltage dependence of the tunneling current from a metallic tip into the Majorana chain as a direct probe of the random critical state.