Physicists observe fractional high-Chern insulators in twisted graphene
This digest was compiled by AI from multiple sources — links to the originals are below.
Researchers observed integer and fractional high-Chern insulators in a moiré system of Bernal bilayer graphene and rhombohedral tetralayer graphene. The findings, published in Nature on July 15, 2026, reveal new quantum states in twisted graphene structures.
The Discovery
A team led by researchers at the University of California, Santa Barbara, observed fractional high-Chern insulators in a moiré system combining Bernal bilayer graphene and rhombohedral tetralayer graphene. The study, published in Nature on July 15, 2026, reports both integer and fractional Chern numbers up to 6. The system was twisted to create a moiré superlattice with a period of approximately 10 nanometers.
Experimental Setup
The device was fabricated using hexagonal boron nitride encapsulation and measured at cryogenic temperatures below 1 Kelvin. Transport measurements revealed quantized Hall resistances at filling factors corresponding to Chern numbers 1, 2, 3, 4, 5, and 6, as well as fractional states at ν = 1/3 and 2/3. The fractional states persisted at magnetic fields as low as 0.5 Tesla.
Implications
The observation of fractional high-Chern insulators in a graphene-based system suggests new platforms for topological quantum computing. The fractional states are predicted to host non-Abelian anyons, which could be used for fault-tolerant qubits. The study provides a route to realizing higher-order topological phases in moiré materials.
What's Next
The team plans to investigate the temperature dependence of the fractional states and search for evidence of non-Abelian statistics. It remains unclear whether these states can be stabilized at higher temperatures or integrated into functional quantum devices.
1 source
Physicists observe fractional high-Chern insulators in twisted graphene
