Tuning single-electron charging and interactions between compressible Landau level islands in graphene
Daniel T. Walkup, Fereshte Ghahari Kermani, Christopher Guti?rrez, Kenji Watanabe, Takashi Taniguchi, Nikolai B. Zhitenev, Joseph A. Stroscio
Interacting quantum dots (QDs), small chunks of matter with well-separated energies of electronic levels, have been extensively exploited in condensed matter physics and quantum information science. Using a low-temperature scanning tunneling microscope (STM), we create and study QDs in graphene, a highly interacting quantum relativistic system. Single or multiple interacting, spatially co- located QDs can be formed through electric and magnetic field confinement as compressible Landau levels sequence through the Fermi level with gating potentials. We show we can map and tune the interaction between these Landau level islands using a combination of magnetic field, back gate potential, and the potential from a scanning tunneling probe. The resulting appearance of energy quantization and Coulomb charging offer the possibility for detailed investigation and control of these interacting quantum systems. An uncommon pattern of avoided single electron crossing and grouping is observed in the charging maps which we explain by a new phenomenological electrostatic model.