Electrical and thermoelectric transport in random-edged graphene quantum dots in the lowest Landau level

Etch-defined graphene quantum dots have inherent randomness on their edges which can generate disorder. Under quantizing magnetic fields, such disorder broadens Landau levels in the system, except the lowest Landau level (LLL) at the charge neutrality point, which remains sharply degenerate due to the chiral symmetry of graphene. The combination of quantum confinement and disorder effects in the partially filled LLL may generate novel non-Fermi liquid behavior with distinct electrical and thermal signatures. We report measurements of electrical conductance and thermopower through an etch-defined graphene island coupled to high-quality graphene reservoirs in a perpendicular magnetic field at low temperatures. The carrier densities in the island and reservoirs are independently tunable, enabling complete or partial transmission or reflection of quantum Hall edge states from the reservoir through the island at certain gate configurations, despite strong spatial confinement. We will discuss the implications of electrical and thermoelectric transport through the graphene quantum dot under strong magnetic fields, where random edge disorder enables strong interactions between localized states in the dot in the lowest Landau level.