Memristive

Memristive refers to devices and systems that show memory of past electrical activity in their resistance. The term stems from memristor, a portmanteau of memory and resistor. In theory, a memristor is a passive two-terminal element whose resistance depends on the integral of current or voltage, effectively linking charge and magnetic flux. The concept was proposed by Leon Chua in 1971 as the fourth fundamental passive circuit element. Real-world devices exhibiting history-dependent resistance are commonly described as memristive or resistive-switching devices, and gained broad attention after HP Labs' 2008 demonstration of a TiO2-based memristor.

Physical mechanisms vary by platform. In many metal-oxide devices, resistance changes arise from ionic migration and the formation or rupture of conductive filaments, or from modification of an interfacial barrier. Other implementations include phase-change materials and certain spintronic structures. The state variable controlling resistance can be driven by voltage, current, or time, and some devices exhibit threshold behavior and nonvolatile retention.

Applications and status. Memristive behavior underpins resistive RAM (RRAM), pursued as a scalable, nonvolatile memory technology, and memristive concepts are central to neuromorphic computing where synapse-like plasticity is desirable. Dense crossbar arrays enable high storage density but face challenges such as device-to-device variability, endurance, and integration with conventional CMOS. Research continues to improve endurance, uniformity, and stability, and to deepen understanding of the physics governing memristive switching.

See also: Memristor, Resistive RAM, Neuromorphic engineering.