Fabricating flexible room-temperature ferromagnetic resistive switching random access memory (RRAM) device is of fundamental importance to integrate nonvolatile memory and spintronics both in theory and practice for modern information technology, which has the potential to bring about revolutionary new foldable information storage devices. Here, we show that a relatively low operating voltage (+1.4V/-1.5V, the corresponding electric field is around 20000V/cm) drives the dual vacancies evolution in ultrathin SnO2 nanosheets at room temperature, which causes the reversible transition between semiconductor and half-metal, accompanying with an abrupt conductivity change up to 10³ times, exhibiting room-temperature ferromagnetism in both two resistance states. Positron annihilation spectroscopy and electron spin resonance results show that the Sn/O dual vacancies in the ultrathin SnO₂ nanosheets evolve to isolated Sn vacancy under electric field, accounting for the switching behavior of SnO₂ ultrathin nanosheets, on the other hand, the different defects types correspond to different conduction nature, realizing the transition between semiconductor and half-metal. Our result represents a crucial step to create new information storage device realizing reversible transition between semiconductor and half-metal with flexibility and room-temperature ferromagnetism at low energy consumption. The as-obtained half-metal in low resistance state broadens the application of the device in spintronics and the semiconductor to half-metal transition based on defects evolution also opens up a new avenue for exploring random access memory mechanisms and finding new half-metals for spintronics.

J. Am. Chem. Soc., Just Accepted Manuscript
DOI: 10.1021/jacs.5b10212

http://pubs.acs.org/doi/abs/10.1021/jacs.5b10212