Detail Optical investigations of multicomponent quantum Hall systems Bibliografi Author: Manfra, Michael J. ; Goldberg, Bennett B. (Advisor) Topik: PHYSICS; CONDENSED MATTER|MATERIALS SCIENCE|PHYSICS; OPTICS Bahasa: (EN )    ISBN: 0-599-01532-2     Penerbit: Boston University     Tahun Terbit: 1999     Jenis: Theses - Dissertation Fulltext: 9904136.pdf (0.0B; 0 download) Abstract Absorption, photoluminescence, and photoluminescence excitation spectroscopy have been used to investigate the nature of the ground-state and fundamental excitations of the small odd-integer quantum Hall states in single-layer and double-layer two-dimensional electron systems residing in GaAs quantum wells. In the single-layer system at filling factor $/nu =1,$ electron-electron interactions are shown to stabilize the formation of multiparticle spin excitations called skyrmions. The presence of skyrmions is manifest in the rapid loss of spin polarization for small excursions from $/nu =1$ as measured by absorption spectroscopy. Further experimental evidence for the highly correlated nature of the $/nu =1$ state in the single-layer system is given by a study of temperature dependence of the spin-polarization exactly at $/nu =1.$ The spin-polarization as a function of temperature exactly at $/nu =1$ is found to evolve in accord with the thermodynamics of a continuum quantum ferromagnetic model of the $/nu =1$ state. Photoluminescence studies of $/nu =3$ and $/nu =5$ in the single-layer system are shown to be sensitive to the presence of an Anderson-Fano-like resonance in the final state of the two-dimensional electron system. The many-body origin of this effect is evident in the complicated filling factor and temperature dependence of the optical anomalies. Finally we present the first absorption studies of the double-layer two-dimensional electron system in the quantum Hall regime. Around total filling $/nu =1,$ absorption spectra have revealed the complex interplay between single-particle gaps and many-body effects for stabilizing this quantum Hall state. Our measurements are shown to provide the first direct experimental evidence for a not fully pseudospin-polarized ground-state at $/nu =1.$ Opini Anda Klik untuk menuliskan opini Anda tentang koleksi ini! Lihat Sejarah Pengadaan  Konversi Metadata   Kembali

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