Ultra‑low‑energy control of graphene stacking could enable slidetronic memory and logic

Researchers from Tel Aviv University, SlideTro and National Institute for Materials Science recently demonstrated ultra‑low‑energy, fully reversible control over the internal stacking order of graphene, pointing to a new class of slidetronic, multi‑ferroic devices. Their approach enables deterministic switching between different graphitic polytypes - such as transforming Bernal tetralayers into rhombohedral crystals - in nanoscale islands only a few tens of nanometers across, using lateral shear forces below 1 nanonewton and less than 1 femtojoule of energy per switching event.Graphitic polytypes are unique stacking arrangements of graphene layers, and they strongly affect the material’s behavior: electrical conductivity, response to magnetic fields, intrinsic polarization, and even the emergence of unconventional superconductivity can all change when the stacking is reconfigured. Until now, controlled switching between these stacking states required micrometre‑scale domains and relatively large, micronewton‑scale forces, which made practical devices unrealistic. In the new work, the team overcomes this limitation by designing tiny graphene “islands” whose stacking can be switched cleanly and reversibly at the 30‑nanometre scale, with energy costs that are orders of magnitude lower than in conventional memory technologies. The key is a smart nanomechanical design. The researchers insert an intentionally misaligned spacer layer between two aligned graphene bilayers and pattern this spacer with nanometre‑scale cavities. Inside each cavity, the active bilayers sag and come into contact, forming a stable single‑domain stacking configuration, while outside the cavities the layers are separated by an incommensurate, superlubric interface that lets them slide almost without friction. Each cavity thus behaves as an individual stacking bit, where one graphene layer can be slid relative to the other to toggle between distinct polytypes without breaking chemical bonds.Experiments with conducting‑probe force microscopy, backed by force‑field calculations, show that switching is mediated by boundary solitons nucleated at the island edges, which then glide across the cavity to convert one commensurate domain into another. Because the pinning of these solitons is extremely weak and strain relaxation extends tens of nanometres beyond the island, a very small initial push is enough to trigger a complete re‑stacking event—and once it begins, the process often continues spontaneously as the system relaxes to a new low‑energy state. In other words, the external actuation only needs to overcome a tiny barrier; the material “does the rest” on its own. Researchers from Tel Aviv University, SlideTro and National Institute for Materials Science recently demonstrated ultra‑low‑energy, fully reversible control over the internal stacking order of graphene, pointing to a new class of slidetronic, multi‑f... [3146 chars]