Tantalum oxide as an alternative low height tunnel barrier in magnetic junctions

Magnetic tunnel junctions with a barrier of tantalum oxide were prepared by plasma oxidation of sputter-deposited tantalum. They show magnetoresistanc e ratios of 2.5% at room temperature and 4% at low temperatures. The materi al exhibits low barrier heights of similar to0.4 eV. This makes it possible to substantially increase the barrier thickness, compared to a barrier of aluminum oxide. The resulting decrease of coupling between the ferromagneti c layers is easily seen. Tantalum oxide appears to be a candidate for use a s a tunnel barrier of spin-dependent tunneling devices. (C) 2001 American I nstitute of Physics.