Emergent multiferroicity in two-dimensional electron gas of complex oxides for FET-based artificial synaptic junctions

Abstract

Designing multifunctional nanoarchitectures that integrate distinct physical phenomena is paramount for next-generation electronics. Here, we report the emergence of a two-dimensional electron gas (2DEG) coexisting with robust multiferroicity at complex oxide heterointerfaces. Synthesized via atomic layer deposition (ALD), these ultrathin heterostructures comprise a ferroelectric Ti_0.6Sn_0.4O₂ layer coupled with ferromagnetic Cr-doped SnO₂. This unique integration engenders strong spin–charge–lattice interactions within the 2DEG, driven by the coupling between switchable ferroelectric domains and itinerant ferromagnetism. Piezoresponse force microscopy confirms tunable ferroelectric polarization, while magnetotransport measurements, including clear Shubnikov–de Haas oscillations, reveal high-mobility quantum transport within the 2DEG. Critically, the heterostructure exhibits dynamic capacitive-to-inductive transitions and current-induced polarization switching, characteristic of ferroelectric memristive behavior suitable for FET-based artificial synaptic junctions. Programmable pulse transient current responses demonstrate the potential for emulating synaptic plasticity. These findings unveil an all-oxide platform uniquely combining ferroelectricity, ferromagnetism, memristive switching, and quantum transport, paving the way for novel spin-orbitronic devices and energy-efficient neuromorphic computing architectures.