Microscopic mechanism underlying discrete lithium-ion occupancy states

Determine the microscopic mechanism responsible for the discrete Li⁺-occupied states and associated ionic-current plateaus observed at the hBN/few-layer graphene interface, distinguishing between spatial domains, ordered lithium phases, and in-plane staging.

Background

The paper interprets the observed ionic-current plateaus as discrete Li⁺-occupied states because each plateau coincides with a sharp change in the electronic conductance of the host crystal and because the plateau current varies approximately linearly with the independently applied differential gate voltage, as expected for field-driven transport at fixed ionic density.

However, the measurements do not uniquely determine the microscopic origin of these states. The authors identify spatial domains, ordered lithium phases, and in-plane staging as possible explanations, while ruling out interfacial redox states and trap filling based on the measured gate-current symmetry, field dependence, and discrete rather than continuous charge accumulation. Establishing which of the remaining mechanisms governs the states would clarify the physical basis of the device behavior.