  We propose an experimental setup of an interferometer for the observation of
neutral Majorana fermions on topological insulator - superconductor -
ferromagnet junctions. We show that the extended lattice defects naturally
present in materials, dislocations, induce spin currents on the edges while
keeping the bulk time-reversal symmetry intact. We propose a simple two
terminal conductance measurement in an interferometer formed by two edge point
contacts, which reveals the nature of Majorana states through the effect of
dislocations. The zero temperature magneto-conductance changes from even
oscillations with period phi/2 (phi is the flux quantum hc/e) to odd
oscillations with period phi, when non-trivial dislocations are present and the
Majorana states are sufficiently strongly coupled. Additionally, the
conductance acquires a notable asymmetry as a function of the incident electron
energy, due to the topological influence of the dislocations, while resonances
appear at the coupling energy of Majorana states.
