Far infrared magneto-optical studies of a quasi-three-dimensional electron system

Miscellaneous · Wed Jan 01 00:00:00 EST 1992

OSTI ID:7041770

Ying, X

Far infrared (IR) magneto-transmission studies have been performed on high mobility electron systems in modulation doped wide parabolic Al[sub x]Ga[sub 1[minus]x]As quantum wells (WPQWs) at low temperatures (down to 1.3K) and high magnetic fields (up to 15T). The magnetic field is applied either perpendicular or parallel to the electron slab. Cyclotron resonance with a perpendicular magnetic field B reveals a dependence of the cyclotron effective mass and scattering time on electron areal density N[sub s]. A collective cyclotron resonance is observed with an in-plane magnetic field for a pure parabolic quantum well. The resonance is a depolarization shifted cyclotron resonance at high N[sub s], and the combined cyclotron resonance and harmonic oscillation at low N[sub s]. The resonance position is found to be independent of N[sub s], at [omega][sup 2] = [omega][sub c][sup 2] + [omega][sub o][sup 2], where [omega] is the radiation frequency, [omega][sub c] is the cyclotron frequency and [omega][sub o] is the harmonic oscillator frequency of the parabolic potential of the well. The far IR magneto-optical response of an asymmetric wide parabolic well is investigated as a function of N[sub s]. The optical response crosses over from single particle transitions at low electron density to 3 dimensional collective (plasma) excitations at high density. The crossover density, scaling as the product of the well curvature and the magnetic length ([ell][sub o]), establishes an experimental criteria for quasi-3 dimensionality in WPQWs. Internal modes of the quasi-3 dimensional electrons in WPQWs are excited using perturbation potentials inserted into the parabolic potential profile of the quantum wells. The magnetic field is applied in the plane of a [approximately] 2/[ell][sub o]. The results represent the first measurement of the magneto-roton dispersion in an electron system.

• Research Organization: Maryland Univ., College Park, MD (United States)
• OSTI ID: 7041770
• Resource Relation: Other Information: Thesis (Ph.D.)
• Country of Publication: United States
• Language: English

Related Subjects

75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
74 ATOMIC AND MOLECULAR PHYSICS
ALUMINIUM ARSENIDES
ELECTRON MOBILITY
MAGNETO-OPTICAL EFFECTS
GALLIUM ARSENIDES
CYCLOTRON RESONANCE
DOPED MATERIALS
FAR INFRARED RADIATION
ALUMINIUM COMPOUNDS
ARSENIC COMPOUNDS
ARSENIDES
ELECTROMAGNETIC RADIATION
GALLIUM COMPOUNDS
INFRARED RADIATION
MATERIALS
MOBILITY
PARTICLE MOBILITY
PNICTIDES
RADIATIONS
RESONANCE
665000* - Physics of Condensed Matter- (1992-)
664000 - Atomic & Molecular Physics- (1992-)