Photo-activated digital resistive switching in a cryogenic photomemory

Resistive switching is the basis of many emerging memory technologies. However, its operation at cryogenic temperatures remains scarce, and it generally lacks compatibility with optical control and in-situ electrical programmability. Here, we report the discovery of a photo-activated digital resistive switching effect in a cryogenic photomemory based on α-In₂Se₃. After an optical pulse, the device can be repeatably switched from a high- to a low-resistance state digitally, which persists long after the photoactivation. The switching threshold voltage can be continuously tuned over a wide range by the reset voltage pulse, additional optical pulses, and electrostatic gating, providing multimodal control over the memory logic. The device also exhibits a markedly enhanced photoresponse and resettable persistent photoconductivity, allowing the emulation of synaptic behaviors at cryogenic temperatures. Our work reveals a defect-mediated mechanism for embedding programmable digital logic into a nonvolatile photomemory, establishing a versatile platform for adaptive optoelectronics at cryogenic temperatures.