Wigner Crystallization and Metal-Insulator Transition of Two-Dimensional Holes in GaAs atB=0

Abstract

We report the transport properties of a low disorder two-dimensional hole system (2DHS) in the GaAs/AlGaAs heterostructure, which has an unprecedentedly high peak mobility of $7\times {10}^5{\mathrm{cm}}^2/\mathrm{V}\mathrm{s}$, with a hole density of $4.8\times {10}^9<p<\mathrm{}3.72\mathrm{}\times {10}^{10}{\mathrm{cm}}^{-2\mathrm{}}$ in the temperature range of $50\mathrm{mK}<T<\mathrm{}1.3\mathrm{}\mathrm{K}$. From their $T$, $p$, and electric field dependences, we find that the metal-insulator transition in zero magnetic field in this exceptionally clean 2DHS occurs at $r_s=35.1\mathrm{}\pm 0.9$, which is in good agreement with the critical $r_s$ for Wigner crystallization $r_s^c=37\mathrm{}\pm 5$, predicted by Tanatar and Ceperley for an ideally clean 2D system.