A complete classification of memristor devices

Several physical and mathematical models have been proposed to describe all 2-terminal non-volatile memory devices based on resistance switching (i.e. memristors), regardless of the device material and physical operating mechanisms. A complete and precise classification of memristor, including memcapacitor and meminductors as well, is instrumental in matching model parameters to physical phenomena and in boosting applications of memristors in unconventional computing systems. The aim of the paper is to provide a theoretical approach to the various classes of mem-devices (i.e. memristors, memcapacitors and meminductors) as nonlinear dynamical systems whose characteristic curves (i.e. dynamic characteristics) are pinched at the origin when driven by bipolar excitations. This theory provides a practical tool to describe mem-devices developed for non-volatile memory applications and neuromorphic systems.