Objective
The primary objective of this project is a comprehensive study of the origin of the zero-field metal-insulator transition and of the corresponding quasimetallic phase which were recently discovered in the 2D electron system in high quality Si-based structures, as well as of the unexpected direct transitions from the quantized Hall conductor to insulator phases in non-zero field.
The proposed research program involves:
a study of the influence of spin-orbit interaction, spin splitting and the symmetry of the confining potential; a study of the role of electron-electron interactions for the metal-insulator transition at zero field;
the verification of the possibility of a metal-insulator transition in 2D systems with pure potential scattering;
an investigation of the phase trajectories of extended states in the zero field limit, and an analogy between the QHE-insulator and metal-insulator transition;
an investigation of the role of electron-electron interactions in the QHE-insulator transition;
the search and studies of the metal-insulator transition in the 2D system of composite fermions.
It is anticipated that, as a result of the project;
the origin and thermodynamics of the zero magnetic field metal-insulator transition in 2D system in Si will be clarified;
the origin and thermodynamics of the direct transitions between the quantized Hall conductor and insulator phase will be understood;
the symmetry theory will be tested and the possibility of the metal-insulator transition in the system with pure potential scattering will be verified;
the effective sigma model will be formulated, which incorporates effects of electron-electron correlations, spin-spin and spin-orbit interaction and the
Chern- Simons statistical gauge fields;
scaling properties, and mapping between the fractional and integer regimes of the QHE will be established, and the theoretical description of the Global Phase Diagram for the quantum Hall effect will be achieved. In particular, the scaling beta function studies on samples with different level of disorder and strength of the many-body interaction will answer the question on universality of the scaling function, its behaviour for the 2D interacting system of distinct symmetry and through a crossover between different regimes which correspond to different symmetry classes. Experiments in a magnetic field will address the question whether the extended states are destroyed by disorder, or persist in the 2D system down to zero magnetic field. As a result of these investigations, the Global Phase Diagram for the 2D quantized system will be more deeply understood.
Topic(s)
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4040 Linz
Austria