Since its isolation in 2004, graphene has been the subject of extensive research and has garnered significant attention due to its remarkable properties.
Recently, a group of physicists at MIT accomplished an impressive feat: they converted commonplace graphite, the material found in pencils, into a new substance exhibiting three unprecedented properties not observed in natural graphite.
The newly developed material, pentalayer rhombohedral stacked graphene, consists of five extremely thin layers of graphene arranged in a specific order.
Scientists previously found that stacking and twisting graphene layers could yield unique properties, a field known as “twistronics.” However, MIT researchers discovered that their pentalayer graphene doesn’t require twisting. Instead, electron correlation within the material leads to the emergence of new properties.
A novel microscope was used to distinguish the ‘Gold’
The team used a novel microscope created at MIT, Named Scattering-type Scanning Nearfield Optical Microscopy (s-SNOM). This microscope enables rapid and cost-effective measurement of diverse characteristics of nanomaterials, including thickness, structure, and optical properties, facilitating the isolation of pentalayer graphene.
Pentalayer rhombohedral stacked graphene is only a few billionths of a meter thick
Utilizing the microscope, the team conducted a scan on a graphite sample to identify areas exhibiting a specific rhombohedral stacking order of five graphene layers.
Three in one: the emergence of three extraordinary properties never seen before in natural graphite
Once pentalayer graphene is isolated, it can transition between three states—insulating, magnetic, and topological—depending on the electron count. In the insulating state, it doesn’t conduct electricity; in the magnetic state, it aligns with a magnetic field, and in the topological state, electricity flows only along the material’s edges, not through its bulk.