Second‐Order Synaptic Memory using Inherent Plasticity of Moiré Superlattices

Abstract

AbstractAchieving synaptic functionality electronically in a single‐element quantum material is a fundamental challenge, as conventional methods rely on the introduction of extrinsic charge‐traps or polar components. Here, it is demonstrated that twisted double bilayer graphene (tDBLG) moiré superlattices—composed purely of carbon—exhibit electronic hysteresis and plasticity in presence of twist‐angle disorder. Inversion symmetry breaking at the moiré length scales also gives rise to second‐order nonlinear electrical response via disorder‐mediated extrinsic mechanisms. Such second‐order nonlinearity is highly tunable in both sign and magnitude by varying carrier concentration and vertical displacement field. The coexistence of electronic plasticity and second‐order nonlinearity is harnessed to realize a second‐order synaptic memory device. These findings establish strained moiré carbon systems as a powerful new platform for energy‐efficient neuromorphic computing, demonstrating that complex electronic functionality can emerge purely from symmetry‐breaking physics in a single‐element material.