Enhancement of tunneling magnetoresistance by inserting an amorphous nonmagnetic FeZr layer in magnetic tunnel junctions

An amorphous metallic FeZr layer is inserted inside the bottom magnetic layer in exchange-biased CoFe/Al2O3/CoFe magnetic tunnel junctions (MTJs). At room temperature, the tunneling magnetoresistance (TMR) increases from 25% to 36% before annealing, and from 45% to 52% after annealing. The junction resistance also increases with the FeZr thickness. The higher quality of the MTJ is attributed to the improved Al-oxide barrier due to the amorphousness of the FeZr layer.