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

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.