Nanowerk November 7, 2023
Ramp-reversal memory has recently been discovered in several insulator-to-metal transition materials where a non-volatile resistance change can be set by repeatedly driving the material partway through the transition. An international team of researchers (USA – Purdue University, University of Colorado, UCSD, France) has successfully developed a single-photon light source consisting of doped ytterbium ions (Yb3+) in an amorphous silica optical fiber at room temperature. They used optical microscopy to track the location and internal structure of accumulated memory as a thin film of VO2 was temperature cycled through multiple training subloops. The measurements revealed that the gain of insulator phase fraction between consecutive subloops occurred primarily through front propagation at the insulator-metal boundaries. By analyzing transition temperature maps they found that the memory was also stored deep inside both insulating and metallic clusters throughout the entire sample. This non-volatile memory was reset after heating the sample to higher temperatures. They proposed that diffusion of point defects accounted for the observed memory writing and subsequent erasing over the entire sample surface.
According to the researchers their results enable the targeting of specific local regions in the film where the full insulator-to-metal resistivity change can be harnessed to maximize the working range of memory for conventional and neuromorphic computing applications… read more. Open Access TECHNICAL ARTICLEÂ
… a) Ramp Reversal temperature protocol. Credit: Advanced Electronic Materials,10 July 2023