Connecting the Reentrant Insulating Phase and the Zero Field   Metal-Insulator Transition in a 2D Hole System
  We present the transport and capacitance measurements of 10nm wide GaAs quantum wells with hole densities around the critical point of the 2D metal-insulator transition (critical density $p_c$ down to 0.8$\times10^{10}$/cm$^2$, $r_s\sim$36). For metallic hole density $p_c < p <p_c +0.15\times10^{10}$/cm$^2$, a reentrant insulating phase (RIP) is observed between the $\nu$=1 quantum Hall state and the zero field metallic state and is attributed to the formation of pinned Wigner crystal. Through studying the evolution of the RIP versus 2D hole density by transport and capacitance experiments, we show that the RIP is incompressible and continuously connected to the zero field insulator, suggesting a similar origin for these two phases. 
Richard L.J. Qiu, Xuan P.A. Gao, L.N. Pfeiffer, K.W. West
cond-mat.str-el cond-mat.mes-hall