  Here, we report the intriguing observation of stable non-volatile resistance
switching (NVRS) in single-layer atomic sheets sandwiched between metal
electrodes. NVRS is observed in the prototypical semiconducting (MX2, M=Mo, W;
and X=S, Se) transitional metal dichalcogenides (TMDs), and insulating
hexagonal boron nitride (h-BN), which alludes to the universality of this
phenomenon in non-metallic 2D monolayers, and features forming-free switching.
This observation of NVRS phenomenon, widely attributed to ionic diffusion,
filament and interfacial redox in bulk oxides and electrolytes, inspires new
studies on defects, ion transport and energetics at the sharp interfaces
between atomically-thin sheets and conducting electrodes. From a contemporary
perspective, switching is all the more unexpected in monolayers since leakage
current is a fundamental limit in ultra-thin oxides. Emerging device concepts
in non-volatile flexible memory fabrics, and brain-inspired (neuromorphic)
computing could benefit substantially from the pervasive NVRS effect and the
associated wide materials and engineering co-design opportunity.
Experimentally, a 50 GHz radio-frequency (RF) monolayer switch is demonstrated,
which opens up a new application for electronic zero-static power RF switching
technology.
