Figure 4.

a) Conductance variations with time when switching field pulses (1000 ms duration) of progressively increasing magnitude (in 4 V steps) are applied every 10 s: in this case, at least ten different stable remnant states have been demonstrated within an order of magnitude change in conductance b) Finer steps of increasing pulsed switching voltage, varied between 0 and 50 V (in 500 mV steps), generated 100 different conductance states within a two orders of magnitude window in conductance. For each state, the time dependence of the conductance is presented, monitored for 10 s after the completion of the switching pulse used to create it. Inset: higher resolution plot of the states created by switching pulses at the upper end of the voltages used.