  Crystallographic and spin polarized transport properties of (100) textured
and (100) epitaxial Fe/MgO/Fe magnetic tunnel junctions are compared. Strong
similarities in the transport properties show that structural coherence and
magnetic quality at the 25 nm grain scale in textured junctions are sufficient
to issue signatures of the spin polarized transport specific to a single
crystal junction. This demonstrates that the lateral coherence of the Bloch
tunneling wave function is identically limited in both systems. Our analysis
leads to model the textured tunnel junction as a juxtaposition of nanometer
sized single crystal junctions, placed in parallel.
