Academic literature on the topic 'Two Dimensional Electron Systems (2DES)'

In this paper, we review the contribution of the Rashba spin–orbit coupling to the magnetoconduction of a two-dimensional electron system (2DES) confined in an inversion layer under quantum Hall regime (low temperature and low defects and impurities). The study is based on a semi-classical model for the magnetoconductivities of the 2DES. This model reproduces the measurements of the Shubnikov-de Haas (SdH) oscillations obtained in systems confined in III–V heterostructures, and also the quantum Hall magnetoconductivity (magnetoresistivity). We also discuss the Rashba and Zeeman competition and its effect on the magnetoconductivity.

Scanning tunneling spectroscopy at T = 6 K is used to investigate the local density of states (LDOS) of electron systems belonging to the bulk conduction band of InAs. In particular, the three-dimensional electron system (3DES) of the n-doped material, an adsorbate-induced two-dimensional electron system (2DES) and the tip-induced quantum dot (0DES) are investigated at B = 0 T and B = 6 T. It is found that the 3DES at B = 0 T can be described by Bloch states weakly interacting with the potential disorder provided by ionized dopants. The 2DES at B = 0 T exhibits much stronger LDOS corrugations, stressing the tendency for weak localization in the potential disorder. In a magnetic field, 3DES and 2DES show drift states, which are expected in 2D, but are surprising in 3D, where they point to a new electron phase consisting of droplets of quasi-2D systems. The 0DES at B = 0 T reveals quantized states in accordance with Hartree calculations. At B = 6 T it exhibits Landau states with exchange enhanced spin splitting. These states are used to investigate the influence of potential disorder on the exchange enhancement, which visualizes the nonlocality of the exchange interaction.

The results of extensive transport studies in localized regime of mesoscopic two-dimensional electron systems (2DES) with varying disorder are presented. A quick overview of previously achieved result is given. The main focus is on the observation of density dependent instabilities manifested by strong resistance oscillations induced by high perpendicular magnetic fields B⊥. While the amplitude of the oscillations is strongly enhanced with increasing B⊥, their position in electron density remains unaffected. The temperature dependence of resistivity shows a transition from an activated behaviour at high temperature to a saturated behaviour at low T. In the positions of resistance minima, the T dependence can even become metal-like (dρ/dT > 0). The activation energies obtained from the high T behaviour exhibit a formation of plateaux in connection with the resistance oscillations when analyzed as a function of electron density. We suggest the interplay between a strongly interacting electron phase and the background disorder as a possible explanation for our observation.

We have developed an optical-fiber-based Hall potential imaging system using the Pockels effect in GaAs/AlGaAs two dimensional electron systems (2DES) in the quantum Hall regime to investigate current distributions. The mapping of the Hall potential shows the current concentration at the bulk region of 2DES samples, where the critical current depends on the channel width sub-linearly. We report in detail the experimental techniques of the imaging system operating in high magnetic fields.