Nematic heavy fermions and coexisting magnetic order in CeSiI

The authors construct here a low-energy model for CeSiI, a new van der Waals (vdW) material that exhibits heavy Fermi liquid behaviour coexisting with magnetic order. Using Abrikosov mean field theory, they observe that the unique geometry of the material facilitates the existence of a nematic heavy Fermi liquid phase as well as a coexistence of heavy Fermi liquid and magnetic order phase. In particular, it is shown that an electric field applied perpendicular to the material consolidates the coexistence phase, demonstrating the high tunability of this new vdW heavy fermion material.