Thin oxide films with perovskite or related structures and with transition metal doping show a
reproducible switching in the leakage current with a memory effect. Positive or negative
voltage pulses can switch the resistance of the oxide films between a low-and a high-
impedance state in times shorter than 100 ns. The ratio between these two states is typically
about 20 but can exceed six orders of magnitude. Once a low-impedance state has been
achieved it persists without a power connection for months, demonstrating the feasibility of …