Two-dimensional electrons electrostatically confined on the surface of graphite

In the bulk of a crystal, charge carriers are described by the Bloch states. At the crystal surface, the lattice periodicity is disrupted transforming itinerant Bloch waves to evanescent states. While easily accessible in semiconductors due to the presence of band gap, surface states are prohibited in gapless metals due to the presence of massive Fermi sea. Here, using capacitance spectroscopy, we show that two-dimensional (2D) charge carriers can be confined on the surface of graphite and electronically decoupled from the bulk simply by electrostatic gating. In the presence of a magnetic field, perpendicular to graphite basal plane, the Landau bands of bulk graphite render to evanescent Landau levels, which, in high magnetic fields, show electron-electron interactions including fractional quantum Hall states and negative electronic compressibility. Our work provides an experimentally convenient and highly tunable system for exploring bulk-surface correspondence.