Showing papers on "Magnetocapacitance published in 1999"
TL;DR: In this paper, the authors employ magnetocapacitance and far-infrared spectroscopy techniques to study the spectrum of the double-layer electron system in a parabolic quantum well with a narrow tunnel barrier in the center.
Abstract: We employ magnetocapacitance and far-infrared spectroscopy techniques to study the spectrum of the double-layer electron system in a parabolic quantum well with a narrow tunnel barrier in the center. For gate-bias-controlled asymmetric electron density distributions in this soft two-subband system we observe both individual subband gaps and double-layer gaps at integer filling factor $\ensuremath{
u}.$ The bilayer gaps are shown to be either trivially common for two subbands or caused by the wave function reconstruction in growth direction as induced by intersubband electron transfer at a normal to the interface magnetic field. In the latter case the observed gaps at $\ensuremath{
u}=1$ and $\ensuremath{
u}=2$ are described within a simple model for the modified bilayer spectrum.
18 citations
TL;DR: In this paper, the capacitance signal is determined by the filling factor that is the difference between the electron and hole filling factors, and a fan chart is generated in order to determine the Fermi level position relative to the electron subbands at different gate voltages.
Abstract: Magnetocapacitance-voltage measurements are performed in hybridized composite quantum wells at 4.2 K. In the quantum Hall regime, the capacitance reveals a series of oscillations resulting from the spin-resolved Landau levels. It is found that the capacitance signal is determined by the filling factor that is the difference between the electron and hole filling factors. A fan chart is generated in order to determine the Fermi level position relative to the electron and hole subbands at different gate voltages. When the Fermi level resides in the middle of the hybridization gap, far infrared photo signals have been detected with photon energy ranging from 1.4 to 5.3 meV. The hybridization gap is determined to be 3 meV.
12 citations
TL;DR: In this article, a theory of currentvoltage characteristic (IVC) is proposed for a gated Corbino disk with a 2D spinless electron system and magnetic filling factors close to an integral value.
Abstract: A theory of current–voltage characteristic (IVC) is proposed for a gated Corbino disk with a 2D spinless electron system and magnetic filling factors close to an integral value. The described results systematically include the features of the electrochemical potential of the 2D electron system in a magnetic field, which are responsible for sharp magnetocapacitance “dips” for integral values of the magnetic filling factor. The theory is used for qualitative interpretation of the observed weakly nonlinear peculiarities of IVC as well as for prediction of local details in the distribution of electron density and electric potential in a current-carrying Corbino disc. Corresponding measurements can be made, for instance, by using the linear electrooptical effect.
1 citations
TL;DR: In this article, a modification of the theory of "incompressible" regions in an ideal spinless inhomogeneous magnetized 2D electronic system near points on the electron density profile n(x) with an integer filling factor is proposed.
Abstract: A modification of the theory of “incompressible” regions in an ideal spinless inhomogeneous magnetized 2D electronic system near points on the electron density profile n(x) with an integer filling factor is proposed. Such regions leads to the appearance of a finite capacitance between the parts of the 2D system that are separated by an incompressible channel, so that capacitive methods can be used to investigate such a system. The Corbino configuration is especially convenient for these purposes. The parameters of the “incompressible” channel in a Corbino disk with a spatially inhomogeneous 2D electronic system in the presence of an individual point, near the channel, on the electron density profile with an integer magnetic filling factor are determined. The magnetocapacitance between the edges of the Corbino disk separated by an incompressible interlayer is found for cases of practical interest. It is shown that this magnetocapacitance contains direct information about the width of the integer strip.
20 Sep 1999
TL;DR: In this article, the propagation direction of fractional quantum Hall effect (FQHE) edge states has been investigated via the symmetry properties of the multi-terminal capacitances of a two dimensional electron gas.
Abstract: The propagation direction of fractional quantum Hall effect (FQHE) edge states has been investigated experimentally via the symmetry properties of the multi-terminal capacitances of a two dimensional electron gas. Although strong asymmetries with respect to zero magnetic field appear, no asymmetries with respect to even denominator Landau level filling factor {nu} are seen. This indicates that current-carrying FQHE edge states propagate in the same direction as integer QHE edge states. In addition, anomalous capacitance features, indicative of enhanced bulk conduction, are observed at {nu} = 1/2 and 3/2.