New Reentrant Insulating Phases in Strongly Interacting 2D Systems with Low Disorder

Richard Qiu,Xuan Gao,Chieh-Wen Liu,Shuhao Liu

doi:10.3390/app8101909

Richard Qiu, Xuan Gao + Show 2 more

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https://doi.org/10.3390/app8101909

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Abstract

The metal-insulator transition (MIT) in two-dimension (2D) was discovered by Kravchenko et al. more than two decades ago in strongly interacting 2D electrons residing in a Si-metal-oxide-semiconductor field-effect transistor (Si-MOSFET). Its origin remains unresolved. Recently, low magnetic field reentrant insulating phases (RIPs), which dwell between the zero-field (B = 0) metallic state and the integer quantum Hall (QH) states where the Landau-level filling factor υ > 1, have been observed in strongly correlated 2D GaAs hole systems with a large interaction parameter, rs, (~20–40) and a high purity. A new complex phase diagram was proposed, which includes zero-field MIT, low magnetic field RIPs, integer QH states, fractional QH states, high field RIPs and insulating phases (HFIPs) with υ < 1 in which the insulating phases are explained by the formation of a Wigner crystal. Furthermore, evidence of new intermediate phases was reported. This review article serves the purpose of summarizing those recent experimental findings and theoretical endeavors to foster future research efforts.

Highlights

Tremendous knowledge from more than fifty years of research has been accumulated regarding the transport behavior of electrons in a variety of two-dimension (2D) materials and systems
The observation of the new reentrant insulating phases (RIPs) in Reference [10] provided a phase diagram consistent with the theory [18], which further suggested that the zero-field metal-insulator transition (MIT) is a a phase diagram consistent with the theory [18], which further suggested that the zero-field MIT is a liquid-Wigner crystal (WC) transition
Wigner crystal transforms into a metallic liquid and the nature of the intermediate phase are still limited and further experiments are required to obtain an in-depth understanding

Summary

Introduction

Tremendous knowledge from more than fifty years of research has been accumulated regarding the transport behavior of electrons in a variety of two-dimension (2D) materials and systems It has regained strong interest in the field of physics and material science due to the recent discoveries of topological insulators [2] and new 2D materials [3]. Bohr radius) is much greater than one In this brief review, we will first introduce and focus on the recently discovered low magnetic field reentrant insulating phases (RIPs) in high quality GaAs 2D systems [10,11,12,13] with a new phase diagram, which connects the zero-field MIT with RIPs, integer QH states, fractional QH states, and.

Longitudinal

Resistivity

Capacitance Measurement

Inductance

Discussion