Study of transport and dielectric of resistive memory states in NiO thin film

We have measured the DC resistance R(T) and AC dielectric constant epsilon(omega) for the bistable high-R and low-R states of NiO thin film. The high-R state shows thermally activated resistance and Debye relaxation of epsilon(omega). In the low-R state, R(T) exhibits a metallic temperature dependence of R(300 K)/R(5 K) = 1.6. The value of epsilon(omega) is drastically different from that of the high-R state, and we interpret it in terms of the free-carrier Drude dielectric response. The plasma frequency omega(2)(p) in the metallic low-R state is estimated to be 1.2 x 10(9)/cm(3).