Temperature, detriment, or advantage for memory emergence: The case of ZnO

Abstract

Despite the widespread emergence of memory effects in solid systems, understanding basic microscopic mechanisms that trigger them is still puzzling. We report how ingredients of solid state transport in polycristalline systems, such as semiconductor oxides, become sufficient conditions for a memristive response that points to the natural emergence of memory, discernible under adequate set of driving inputs. The experimental confirmation of these trends will be presented along with a compact analytical theoretical picture that allows discerning the relative contribution of the main building blocks of memory and the effect of temperature, in particular. These findings can be extended to a vast universe of materials and devices, providing a unified physical explanation for a wide class of resistive memories, and pinpointing the optimal driving configurations for their operation.

Tuning the conductance topology in solids

“…The topology modulation of the hysteretic loops, understood here as the character, direction, and number of crossings of the I-V response, will be described within a unified representation, providing clues of its grounding functioning principles on the basis of common elements of transport properties in solids. Thus, the crossing analysis can be extended beyond the Type I and Type II topological dichotomy [16,17] for the characterization of a wide variety of memeristive responses. A diagrammatic, universal perspective for this characterization in terms of phasors for the time resolved admittance description is also being introduced.…”

“…The time evolution of the number of carriers, n, under sweeping voltage, V = V 0 cos(ωt), can now be obtained in the relaxation time approximation by solving, dn/dt = g(V ) − n/τ , with τ representing the nonequilibrium carrier life time. The current flowing through the system is given by I = (G 0 + γ n) V , where G 0 is the conductance of the unperturbed state [16] and γ = eµ/L z , proportional to the carrier mobility µ [17]. In the steady regime, (large time limit) which is independent on the initial conditions, the solution is,…”