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Title: Dynamics of Coulomb correlations in semiconductors in high magnetic fields

Abstract

Current theories have been successful in explaining many nonlinear optical experiments in undoped semiconductors. However, these theories require a ground state which is assumed to be uncorrelated. Strongly correlated systems of current interest, such as a two dimensional electron gas in a high magnetic field, cannot be explained in this manner because the correlations in the ground state and the low energy collective excitations cause a breakdown of the conventional techniques. We perform ultrafast time-resolved four-wave mixing on $n$-modulation doped quantum wells, which contain a quasi-two dimensional electron gas, in a large magnetic field, when only a single Landau level is excited and also when two levels are excited together. We find evidence for memory effects and as strong coupling between the Landau levels induced by the electron gas. We compare our results with simulations based on a new microscopic approach capable of treating the collective effects and correlations of the doped electrons, and find a good qualitative agreement. By looking at the individual contributions to the model, we determine that the unusual correlation effects seen in the experiments are caused by the scattering of photo-excited electron-hole pairs with the electron gas, leading to new excited states which are notmore » present in undoped semiconductors, and also by exciton-exciton interactions mediated by the long-lived collective excitations of the electron gas, inter-Landau level magnetoplasmons.« less

Authors:
 [1]
  1. Univ. of California, Berkeley, CA (United States)
Publication Date:
Research Org.:
Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
OSTI Identifier:
799597
Report Number(s):
LBNL-50215
R&D Project: 504901; B& R KC0202020; TRN: US0202317
DOE Contract Number:  
AC03-76SF00098
Resource Type:
Thesis/Dissertation
Resource Relation:
Other Information: TH: Thesis (Ph.D.); Submitted to Univ. of California, Berkeley, CA (US); PBD: 1 May 2002
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; BREAKDOWN; COLLECTIVE EXCITATIONS; ELECTRON GAS; ELECTRONS; EXCITED STATES; GROUND STATES; MAGNETIC FIELDS; SCATTERING

Citation Formats

Fromer, Neil Alan. Dynamics of Coulomb correlations in semiconductors in high magnetic fields. United States: N. p., 2002. Web. doi:10.2172/799597.
Fromer, Neil Alan. Dynamics of Coulomb correlations in semiconductors in high magnetic fields. United States. doi:10.2172/799597.
Fromer, Neil Alan. Tue . "Dynamics of Coulomb correlations in semiconductors in high magnetic fields". United States. doi:10.2172/799597. https://www.osti.gov/servlets/purl/799597.
@article{osti_799597,
title = {Dynamics of Coulomb correlations in semiconductors in high magnetic fields},
author = {Fromer, Neil Alan},
abstractNote = {Current theories have been successful in explaining many nonlinear optical experiments in undoped semiconductors. However, these theories require a ground state which is assumed to be uncorrelated. Strongly correlated systems of current interest, such as a two dimensional electron gas in a high magnetic field, cannot be explained in this manner because the correlations in the ground state and the low energy collective excitations cause a breakdown of the conventional techniques. We perform ultrafast time-resolved four-wave mixing on $n$-modulation doped quantum wells, which contain a quasi-two dimensional electron gas, in a large magnetic field, when only a single Landau level is excited and also when two levels are excited together. We find evidence for memory effects and as strong coupling between the Landau levels induced by the electron gas. We compare our results with simulations based on a new microscopic approach capable of treating the collective effects and correlations of the doped electrons, and find a good qualitative agreement. By looking at the individual contributions to the model, we determine that the unusual correlation effects seen in the experiments are caused by the scattering of photo-excited electron-hole pairs with the electron gas, leading to new excited states which are not present in undoped semiconductors, and also by exciton-exciton interactions mediated by the long-lived collective excitations of the electron gas, inter-Landau level magnetoplasmons.},
doi = {10.2172/799597},
journal = {},
number = ,
volume = ,
place = {United States},
year = {2002},
month = {1}
}

Thesis/Dissertation:
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