Frequency -dependent resistivity for a two -dimensional electron gas with electrostatic modulation.
Item
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Title
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Frequency -dependent resistivity for a two -dimensional electron gas with electrostatic modulation.
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Identifier
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AAI3245078
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identifier
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3245078
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Creator
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Fekete, Paula.
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Contributor
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Adviser: Godfrey Gumbs
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Date
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2007
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Language
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English
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Publisher
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City University of New York.
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Subject
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Physics, Theory
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Abstract
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We present a model calculation for the photoconductivity of a two-dimensional electron gas (2DEG) in an ambient perpendicular magnetic field. An electrostatic modulation is also applied to produce quantum wires (QW), dots (QD) or antidots (QA) in the 2DEG. This system is then subjected to a weak radiation field with its frequency lying in the microwave range. The Landau eigenstates of the periodically modulated system are first found numerically and then used in the Kubo formula to obtain the frequency-dependent longitudinal (rho xx) and transverse (rhoxy) resistivities. These quantum magnetotransport (QMT) coefficients are investigated in the low magnetic field region (B < 0.3T) over a range of frequencies (O) of the external, time-dependent radiation field. The effects of scattering are considered for square arrays of quantum dots and antidots, as well as one-dimensional (1D) quantum wires. The quantum dots, antidots, and wires are simulated by potential forms widely used in the relevant literature. The effect of changing the scatterer type and strength is investigated. The contribution to the QMT coefficients from states near and below the Fermi level is examined when the magnetic field strength and density of charge carriers is varied. The effect of sub-Landau level state formation on the QMT coefficients is also analyzed. The dependence of the QMT coefficients on commensurability effects in the magnetic field and scattering potential is described. Numerical investigations are conducted which show how the magnetic field strength, modulating potential intensity, lattice scattering, electron density, and radiation field frequency affect the AC longitudinal and Hall resistivities. The calculation is restricted to the low-frequency regime where the system is assumed to be in or close to equilibrium.
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Type
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dissertation
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Source
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PQT Legacy CUNY.xlsx
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degree
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Ph.D.
