Quantum Solids of Two Dimensional Electrons in Magnetic Fields
Abstract
This thesis studies the solid phases of two-dimensional electrons subject to a perpendicular magnetic field (i.e., the "quantum Hall system"). Traditionally, such a solid known as "Wigner cystal" (WC), is believed to be the ground state of a two dimensional electron system (2DES) when the Landau level (LL) filling factor =nh/eB (n being the electron density and B the magnetic field) is sufficiently small (thus following the termination of quantum Hall states). Due to disorder in realistic samples, the solid is pinned, therefore insulating. Collective oscillation of crystalline domains of the solid around disorder gives rise to a "pinning mode" resonance in the frequency dependent conductivity, which we measure with rf/microwave spectroscopy. The resonance has interesting behaviors in its dependence on samples, n, B and temperature (T) and contains valuable information about disorder. For example we are able to show that the most relevant disorder that pins the solid comes from the interface that vertically confines the 2DES, with a (sample dependent) disorder correlation length that can become shorter than 10 nm. Most importantly, the resonance is a characteristic signature of pinned electron solids, as well as a tool to study their physical properties. We show that many such solid phases can exist, in different regimes of ; and their properties also depend largely on , which captures the quantum correlation between electrons.
Document Details
- Document Type
- Technical Report
- Publication Date
- Nov 01, 2005
- Accession Number
- ADA575677
Entities
People
- Yong P. Chen
Organizations
- Princeton University