Connecting the Reentrant Insulating Phase and the Zero-Field Metal-Insulator Transition in a 2D Hole System

Abstract

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 pc down to 0.8×10 10 /cm 2 , rs∼36). For metallic hole density pc<p<pc+0.15×10 10 /cm 2 , a reentrant insulating phase (RIP) is observed between the ν=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.

Impact of short-range scattering on the metallic transport of strongly correlated two-dimensional holes in GaAs quantum wells

“…Although strong electron-electron interactions are believed to be an essential factor in the origin of this MIT in 2D, the effects of disorder seem to be non-negligible and must be incorporated in order to reconcile the subtle differences in all the 2D MIT experiments over a range of disorder and interaction strength [2,3,[13][14][15]. While the understanding of the 2D MIT in the critical regime continues to advance [13][14][15][16][17], the mechanism of the 2D metallic conduction in the metallic regime (resistivity <<h/e 2 ) remains an outstanding problem under debate [4,18]. Since metallic transport is the central phenomenon that challenges conventional wisdom based on localization and weakly interacting Fermi liquid theory, its understanding would shed light on the 2D MIT and transport of correlated 2D electron fluids in general.…”

Experimental study of two-dimensional quantum Wigner solid in zero magnetic field

“…[T * -activation energy; ν = 1 is for Arrhenius; ν = 1/3 and 1/2 for variable range hoppings (VRH) [2,9]]. Therefore, a systems with minimal disorder is required so that interaction remains dominant even for r s > 37.We note that the rigorous requirement for the low disorder can be alleviated in the fractional quantum Hall regime in a strong magnetic field where peculiar insulating phases characterized also by activated conductance, near filling factors 1/5, 1/3, and 1, have been considered as candidates for a WC [11][12][13][14]. However, the electron wavefunctions and interaction potentials are radically modified by the large field and the many-electron states are drastically altered.…”

Qiu and Gao Reply:

“…RC network model [11,12] shows the low frequency C measurement in [2] being in the frequency independent regime. The small phase shift of charging current [10] allows an estimate of the error in C to be within 1% for the lowest hole density displaying up to 50% capacitance drop in the RIP (Fig.2 of Ref.…”

“…The small phase shift of charging current [10] allows an estimate of the error in C to be within 1% for the lowest hole density displaying up to 50% capacitance drop in the RIP (Fig.2 of Ref. [2]). These facts exclude the resistive and slow charging explanations suggested by KP.…”

“…These facts exclude the resistive and slow charging explanations suggested by KP. We also note that the resistance measurement in [2] was done with voltage on sample approaching μV range, avoiding the threshold I-V [3,4,13] or heating effects [14].…”