Tunnel magnetoresistance in epitaxial (100)-oriented FeCo/LiF/FeCo magnetic tunnel junctions

We fabricated fully epitaxial magnetic tunnel junctions with LiF tunnel barriers on Si (100) substrates with high-vacuum electron-beam deposition. By changing the thickness of the LiF barrier, tunnel magnetoresistance of up to 90% at 77 K (17% at room temperature) was observed at $tLiF$ = 2.8 nm. The magnetoresistance ratio as a function of the LiF barrier thickness shows a similar trend with that in magnetic tunnel junctions using epitaxial MgO barriers. There is a rapid decrease of the magnetoresistance ratio with increasing bias-voltage and temperature, indicating the presence of imperfections in the LiF barriers.