Finite Capacitive Response at the Quantum Hall Plateau
Lili Zhao1, Wenlu Lin1, Y. J. Chung2, K. W. Baldwin2, L. N. Pfeiffer2, and Yang Liu1*
1International Center for Quantum Materials, Peking University, Beijing 100871, China 2Department of Electrical Engineering, Princeton University, Princeton, New Jersey 08544, USA
Abstract:We study ultra-high-mobility two-dimensional (2D) electron/hole systems with high precision capacitance measurement. It is found 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 $T\gtrsim 300$ mK, which surprisingly disappears at $T\lesssim 100$ mK. This anomalous behavior is likely a manifestation that dilute particles/vacancies in the top-most Landau level form Wigner crystals, which have finite compressibility and can host polarization current.
. [J]. 中国物理快报, 2022, 39(9): 97301-.
Lili Zhao, Wenlu Lin, Y. J. Chung, K. W. Baldwin, L. N. Pfeiffer, and Yang Liu. Finite Capacitive Response at the Quantum Hall Plateau. Chin. Phys. Lett., 2022, 39(9): 97301-.
In samples A, B and C, our measured capacitance approaches a constant value $\simeq$60 fF when the particles form incompressible integer quantum Hall liquid. This is likely the parasitic capacitance $C_{\rm P}$ induced by the bonding wires, gates, etc. In sample D, $C_{\rm P}$ is reduced to $\simeq$15 fF because we add one impedance matching network at the input of the bridge at the sample stage. We have subtracted $C_{\rm P}$ in all figures.