Super‐Resolution Imaging of Nanoscale Inhomogeneities in hBN‐Covered and Encapsulated Few‐Layer Graphene

Encapsulating few-layer graphene (FLG) in hexagonal boron nitride (hBN) cancause nanoscale inhomogeneities in the FLG, including changes in stackingdomains and topographic defects. Due to the diffraction limit, characterizingthese inhomogeneities is challenging. Recently, the visualization of stackingdomains in encapsulated four-layer graphene (4LG) has been demonstratedwith phonon polariton (PhP)-assisted near-field imaging. However, theunderlying coupling mechanism and ability to image subdiffractional-sizedinhomogeneities remain unknown. Here, direct replicas and magnifiedimages of subdiffractional-sized inhomogeneities in hBN-covered trilayergraphene (TLG) and encapsulated 4LG, enabled by the hyperlensing effect,are retrieved. This hyperlensing effect is mediated by hBN’s hyperbolic PhPthat couple to the FLG’s plasmon polaritons. Using near-field microscopy, thecoupling is identified by determining the polariton dispersion in hBN-coveredTLG to be stacking-dependent. This work demonstrates super-resolution andmagnified imaging of inhomogeneities, paving the way for the realization ofhomogeneous encapsulated FLG transport samples to study correlatedphysics