Interlayer-Exciton Based Nonvolatile Valleytronic Memory

TL;DR

This paper demonstrates a novel nonvolatile valleytronic memory device using interlayer excitons in WS2/WSe2 heterostructures, showing large hysteresis and retention over 60 minutes, advancing valleytronics technology.

Contribution

It introduces the first nonvolatile valleytronic memory based on interlayer excitons with demonstrated retention and hysteresis effects.

Findings

Large excitonic/valleytronic hysteresis observed

Memory retention exceeds 60 minutes

Chemical doping influences hysteresis behavior

Abstract

Analogous to conventional charge-based electronics, valleytronics aims at encoding data via the valley degree of freedom, enabling new routes for information processing. Long-lived interlayer excitons (IXs) in van der Waals heterostructures (HSs) stacked by transition metal dichalcogenides (TMDs) carry valley-polarized information and thus could find promising applications in valleytronic devices. Although great progress of studies on valleytronic devices has been achieved, nonvolatile valleytronic memory, an indispensable device in valleytronics, is still lacking up to date. Here, we demonstrate an IX-based nonvolatile valleytronic memory in a WS2/WSe2 HS. In this device, the emission characteristics of IXs exhibit a large excitonic/valleytronic hysteresis upon cyclic-voltage sweeping, which is ascribed to the chemical-doping of O2/H2O redox couple trapped between the TMDs and substrate. Taking advantage of the large hysteresis, the first nonvolatile valleytronic memory has been successfully made, which shows a good performance with retention time exceeding 60 minutes. These findings open up an avenue for nonvolatile valleytronic memory and could stimulate more investigations on valleytronic devices.