Identification of abrupt intense rhombohedral stacking-transitions in dense-staircase-sublattices created by manual exfoliation of highly oriented pyrolytic graphite

Controlling Bernal (AB) to rhombohedral (ABC) stacking-transitions has recently become an important goal towards manipulation of the electronic properties of highly- oriented-pyrolytic-graphite (HOPG) and graphene. In this letter we report a novel investigation of AB to ABC stacking transitions in exfoliated-HOPG-lamellae with variable thickness. The samples were produced by employing I) an edge-tape-exfoliation-method to extrude lamellae of similar to 80-140 mu m thickness and 2) a manual-exfoliation-method, which yielded samples of similar to 300-450 mu m thickness. Characterization was carried out by employing Raman-point/mapping-spectroscopy in certain selected defective-regions of the samples. We demonstrate an abrupt enhancement of the rhombohedral-phase-content within dense- and thick-staircase-sublattices, indicative of a possible crucial role of the sublattice-defect-thickness in preventing ABC to AB post-exfoliation stacking-relaxation. Relaxation of the produced ABC stacks was then found after approximately four weeks from exfoliation (in thick lamellae). (c) 2021 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/)

Automated summary

This study investigates the AB to ABC stacking transitions in exfoliated-HOPG-lamellae and suggests a crucial role of sublattice-defect-thickness in preventing stacking-relaxation. Relaxation of ABC stacks was observed approximately four weeks after exfoliation.