“…For example, EIS allows one to identify relatively easily whether the switching layer consists of a single or several sub-layers [25], contains the additional electrode interface active in a switching layer [34] or several material layers, as in Dash et al [29], where double arcs were identified in Nyquist plots and linked to TiO x and TiO 2 layers. Furthermore, it can be easily seen whether the impedance is dominated by the capacitive or inductive elements; the latter assumed to be linked to conductive, mostly metallic filaments [19,20,27] whilst a leaky insulating layer, typically in HRS, is modeled as a capacitor with a parallel resistance [20,23,25,30]. Sometimes, one also observes a phenomenon at lower frequencies often referred to as the 'inductive hook' related to diffusion of ions [25,26,34,35] and visible as an inductive arc contribution at lower frequencies.…”