Evidence of electron crystal in crystalline rhombohedral graphene

Electrons self-organize into a crystal when Coulomb repulsion becomes much larger than their kinetic energy, known as a Wigner crystal. Zero-field Wigner crystals demand ultraclean samples and have usually offered only a single tuning knob, the carrier density, in past realizations. Crystalline rhombohedral multilayer graphene provides a clean and highly tunable platform to explore these electron crystals, as its gate-tunable flat band allows control not only of carrier density but also of the underlying band dispersion. Here we show evidence of a Wigner crystal in dual-gated crystalline rhombohedral graphene devices, revealed through transport and capacitance measurements. I will also discuss a distinct state that emerges near the melting transition of the crystal.