STDP (Spike-Timing-Dependent Plasticity): STDP describes how the response of a synapse is affected by dual stimulation from pre-synaptic and post-synaptic neurons, where the two stimuli are not applied simultaneously. The response current of the synapse is dependent on the time interval (∆t) between the two stimuli and the voltage difference (∆V) between them. The conductance of the device varies with ∆t. Each ∆t corresponds to different peak voltage and duration of high voltage, leading to changes in the polarization state of the ferroelectric stack, resulting in varying conductance values. The relationship between ∆G (change in conductance) and ∆t is shown in Figure 4e.