Exploring 2D Metal-Insulator Transition in P-GaAs Quantum Well with High Rs PDF Download

Author: Lei Qiu
Publisher:
ISBN:
Category : Low-dimensional topology
Languages : en
Pages : 106

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Book Description
This thesis consists of four main parts. The first part introduces the history of the concept of a Wigner crystal and recent theoretical developments based on this concept, which mainly raises the idea of having intermediate phases near the boundary of the Wigner crystal-liquid transition. It also briefly introduces another long standing puzzle: 2D zero field metal-insulator transition. The second part studies the solid phase known as the "Wigner crystal" (WC) of two-dimensional holes observed in weak perpendicular magnetic field. Magnetoresistivity and thermodynamic compressibility in several densities and temperatures are measured and discussed. It strongly suggests that the metal-insulator transition should be closely related to the WC-liquid transition since the experimental phase diagram coins with theoretical phase diagram. The third part investigates the phase transition between observed the solid phase and liquid state. A new intermediate phase called a micro-emulsion phase is discovered. Its isotropic feature and response to disorder level are discussed. Finally, the fourth part introduces a new perspective, which is derived from the conclusions of the second and third part, towards the two-decade puzzle named the two dimensional metal-insulator transition (2D MIT). Scaling behavior of resistivity of dilute holes in GaAs quantum well on the insulating side of 2D MIT is found for the first time. Overall, our studies indicate the observation of a new WC phase at low magnetic field. Through studying its transition to liquid state, a new intermediate phase is identified. By applying the new perspective gained, the scaling of resistivity is observed and strongly suggests that the 2D MIT is a quantum phase transition of WC and micro-emulsion phases.