Co $_2$FeSi Based Magnetic Tunnel Junctions With BaO Barrier

BaO has been introduced as a novel tunnel barrier material in magnetic tunnel junctions (MTJs). Due to the good agreement regarding lattice constants and crystal structure, we believe BaO to be particularly suitable as barrier in MTJs containing Heusler compound electrodes. Co
₂
FeSi/BaO/Fe MTJs have been fabricated by molecular beam epitaxy (MBE) and investigated in terms of microstructure, transport properties and tunnel magneto resistance (TMR). A TMR amplitude as high as 104% at room temperature (RT) has been achieved for very small bias voltages (
V
_Bias
) and a strong dependence on
V
_Bias
could be observed as the TMR ratio decreases with increasing
V
_Bias
to about 14% at
V
_Bias
= 10 mV.