Analog Memristors Based on Thickening/Thinning of Ag Nanofilaments in Amorphous Manganite Thin Films

We developed an analog memristor based on the thickening/thinning of Ag nanofilaments in amorphous La1-xSrxMnO3 (a-LSMO) thin films. The Ag/a-LSMO/Pt memristor exhibited excellent pinched hysteresis loops under high-excitation frequency, and the areas enclosed by the pinched hysteresis loops shrank with increasing excitation frequency, which is a characteristic typical of a memristor. The memristor also showed continuously tunable synapselike resistance and stable endurance. The a-LSMO thin films in the memristor acted as a solid electrolyte for Ag+ cations, and only the Ag/a-LSMO/Pt memristor electroformed with a larger current compliance easily exhibited high-frequency pinched hysteresis loops. On the basis of the electrochemical metallization (ECM) theory and electrical transport models of quantum wires and nanowires, we concluded that the memristance is ultimately determined by the amount of charge supplied by the external current. The state equations of the memristor were established, and charge was the state variable. This study provides a new analog memristor based on metal nanofilaments thickening/thinning in ECM cells, which can be extended to other resistive switching materials. The new memristor may enable the development of beyond von Neumann computers.