Capacitive Response of Wigner Crystals at the Quantum Hall Plateau
Abstract
In this report, we study ultra-high-mobility two-dimensional (2D) electron/hole systems with high precision capacitance measurement. We find that the capacitance charge appears only at the fringe of the gate at high magnetic field when the 2D conductivity decreases significantly. At integer quantum Hall effects, the capacitance vanishes and forms a plateau at high temperatures T 300 mK, which surprisingly, disappears at T 100 mK. This anomalous behavior is likely a manifestation that the dilute particles/vacancies in the top-most Landau level form Wigner crystal, which has finite compressibility and can host polarization current.
0