Optical Detection of Sliding Ferroelectric Switching in hBN with a WSe₂ Monolayer

When two BN layers are stacked in parallel in an AB or BA arrangement, a spontaneous out-of-plane electric polarization arises due to charge transfer in the out-of-plane B-N bonds. The ferroelectric switching from AB to BA (or BA to AB) can be achieved with a relatively small out-of-plane electric field through the in-plane sliding of one atomic layer over the other. However, the optical detection of such ferroelectric switching in hBN has not yet been demonstrated. In this study, we utilize an adjacent WSe₂ monolayer to detect the ferroelectric switching in BN. This dynamic coupling between a two-dimensional (2D) ferroelectric and a 2D semiconductor allows for the fundamental investigation of the ferroelectric material using a nondestructive, local optical probe, offering promising applications for compact and nonvolatile memory devices.