| Physicists at the Laboratoire de Physique des Solides (CNRS/Université Paris-Saclay), in collaboration with Japanese and Ukrainian partners, have shown that incorporating lead iodide into a moiré material enables the emergence of strongly correlated electronic states and near-dissipationless transport, thanks to ballistic channels induced by the moiré pattern. |
Since 2018, condensed-matter physicists have been increasingly interested in so-called moiré materials—stacks of atomically thin crystalline layers that are slightly twisted or otherwise misaligned. These small misalignments profoundly modify how electrons move and interact, potentially inducing superconductivity and other unusual electronic phenomena.
In this context, Alexei Chepelianskii (Université Paris-Saclay) and collaborators have demonstrated that these properties can be enriched by incorporating lead iodide (PbI₂), a semiconductor characterized by strong intrinsic coupling between electron spin and orbital motion. This strong spin–orbit coupling provides a powerful lever for engineering topological quantum states.
The team fabricated a moiré material consisting of four layers of PbI₂, covered by a layer of hexagonal boron nitride and a layer of graphene, with carefully controlled twist angles between each component. Cooled to ultralow temperatures and subjected to a strong magnetic field, this system exhibits remarkable transport properties.
The researchers observe an electrical conductance equal to two-thirds of the conductance quantum, a hallmark of strongly correlated electronic states. This fractional quantization is a clear signature of exotic quantum phases beyond conventional band theory.
Moreover, at the charge neutrality point—where positive and negative charges balance—electric current flows with almost no energy loss. The longitudinal resistance drops to zero, indicating transport without electron scattering. The researchers attribute this behavior to ballistic conduction channels induced by the moiré pattern and enabled by the strong spin–orbit coupling of PbI₂. This near-dissipationless transport opens new perspectives for low-power quantum electronic devices.
Contributeur·ice·s
Yan Sun,1 M. Monteverde,1 V Derkach,2 K. Watanabe,3 T. Taniguchi,4 F. Chiodi,5 H. Bouchiat,1 and A.D. Chepelianskii
Équipes
Laboratoire de Physique des Solides (CNRS / Université Paris-Sacl