  Complementary resistive switches (CRS) are considered as a potential solution
for the sneak path problem in large-scale integration of passive crossbar
resistive memory arrays. A typical CRS is composed of two bipolar memory cells
that are connected anti-serially. Here we report a tantalum-oxide based
resistive memory that achieves the complementary switching functionality within
a single memory cell. The complementary switching effect is accompanied by
switching polarity reversal in different voltage bias regimes. These effects
were explained by the redistribution of oxygen vacancies inside the
tantalum-oxide layers. The effects of symmetry breaking on bipolar switching
and complementary switching were also discussed.
