Realization and regulation of artificial synaptic functions in multiferroic Sm-doped SnS₂

Ferroelectric materials exhibit switchable polarization and non-volatile characteristics, promising for applications in neural morphology calculations. Among them, multiferroic materials have garnered significant attention due to their simultaneous ferroelectricity and ferromagnetism. We synthesize Sm-doped SnS 2 wafer with interlayer screw dislocations through the vapor-liquid phase chemical deposition, high-temperature and high-pressure methods. Manufacturing a memory device based on Sm-doped SnS 2 wafer, which exhibits stable memory characteristics with a retention time of 10 6  s and can be repeated for up to 10 6  cycles. It can simulate the functional characteristics of biological synapses, such as excitatory postsynaptic currents, paired-pulse facilitation, and the transition from short-term to long-term plasticity. The recognition accuracy rate for handwritten numbers is as high as 92.5 %. Therefore, the addition of Sm leads to the formation of interlayer screw dislocations in the SnS 2 layers, which disrupts the symmetry of the system and causes the ferroelectric properties to emerge. The substitution of Sm for Sn closely integrates with the SnS 2 lattice, providing a stable local magnetic moment. The 4f electrons occupy the energy band near the Fermi level and undergo orbital hybridization with S, resulting in the formation of ferromagnetic exchange interactions, achieving the ferromagnetism. This work opens prospects for fabricating synaptic devices based on ferroelectric switching, which can be used in neuromorphic systems.