“…Based on the direction of I – V response and the switching direction (Figures S1 and S2 and details given in Supplementary Note 1), the I – V curves of this model exhibits, in total, eight types of nonpinched characteristic behavior, namely, C 1 M 1 , C 1 M 2 , C 1 M 3 , C 1 M 4 , C 2 M 1 , C 2 M 2 , C 2 M 3 , and C 2 M 4 , as shown in Figure . Among these nonlinear nonpinched I – V hysteresis behaviors, C 1 M 1 , C 1 M 2 , and C 1 M 4 have be found in some experimental reports. − Although the C 1 M 3 type I – V curve has not yet been reported, as far as we know, the similar C 2 M 4 type I – V curve has already been described by circuit simulation . To the best of our knowledge, the results in Figure contain all reported nonpinched I – V hysteretic behaviors thus far known, strongly supporting the validity of our simulation.…”