Electronic Compressibility of Magic-Angle Graphene Superlattices

• Main Authors: Tomarken, Spencer Louis (Author), Cao, Yuan (Author), Demir, Ahmet (Author), Jarillo-Herrero, Pablo (Author), Ashoori, Raymond (Author)
• Other Authors: Massachusetts Institute of Technology. Department of Physics (Contributor)
• Format: Article
• Language: English
• Published: American Physical Society (APS), 2020-09-10T14:56:10Z.
• Subjects: Article
• Online Access: Get fulltext

 We report the first electronic compressibility measurements of magic-angle twisted bilayer graphene. The evolution of the compressibility with carrier density offers insights into the interaction-driven ground state that have not been accessible in prior transport and tunneling studies. From capacitance measurements, we determine the chemical potential as a function of carrier density and find the widths of the energy gaps at fractional filling of the moiré lattice. In the electron-doped regime, we observe unexpectedly large gaps at quarter- and half-filling and strong electron-hole asymmetry. Moreover, we measure a ∼35 meV minibandwidth that is much wider than most theoretical estimates. Finally, we explore the field dependence up to the quantum Hall regime and observe significant differences from transport measurements.