Nonlocal conductance of topological insulator F/S/I/S/F junction

In this work the non-local conductance (nlc) in the topological insulator ferromagnetic/superconductor/insulator/superconductor/ferromagnetic (f/s/i/s/f) structure is numerically investigated. the insulator region is a thin barrier and the magnetization of the ferromagnetic regions is considered perpendicular to the surface of the topological insulator. our results indicate, when the magnetization vectors in the ferromagnetic regions are parallel (anti-parallel), the crossed andreev reection (electron elastic cotunneling) process does not occur and also the nlc in terms of barrier strength shows a π periodic behaviour. in addition, the nlc as a function of the barrier strength shows an on-off quantum switching properties. we find also that this junction can be used as a quantum entangler devise which is of high important in quantum computing.