In-Plane Magnetic Field Induced Anisotropy of 2D Fermi Contours and the Field Dependent Cyclotron Mass

There has been a surge of recent interest in the role of anisotropy in interaction-induced phenomena in two-dimensional (2D) charged carrier systems. A fundamental question is how an anisotropy in the energy-band structure of the carriers at zero magnetic field affects the properties of the interacting particles at high fields, in particular of the composite fermions (CFs) and the fractional quantum Hall states (FQHSs). We demonstrate here tunable anisotropy for holes and hol...

In this paper, we analyze several experiments that address the effects of electron-electron interactions in 2D electron (hole) systems in the regime of low carrier density. The interaction effects result in renormalization of the effective spin susceptibility, effective mass, and g*-factor. We found a good agreement among the data obtained for different 2D electron systems by several experimental teams using different measuring techniques. We conclude that the renormalization...

Momentum and energy balance equations are developed for steady-state electron transport and optical absorption under the influence of a dc electric field, an intense ac electric field of terahertz (THz) frequency in a two-dimensional (2D) semiconductor in the presence of a strong magnetic field perpendicular to the 2D plane. These equations are applied to study the intensity-dependent cyclotron resonance (CR) in far-infrared transmission and THz-radiation-induced photoconduct...

We have measured the zero-bias differential tunneling conductance of InAs/AlSb/GaS b/AlSb/InAs heterostructures at low temperatures (1.7K < T < 60K) and unde r a magnetic field at various angles with the heterostructure's interfaces. Shubni kov-de Haas oscillations in the magnetoconductance reveal the two-dimensional (2D) character of the electrons accumulated at the InAs interfaces and yield their num ber in each of them. The temperature dependence of the oscillations sugges...

In ultra-clean 2D electron systems on (001) GaAs/AlGaAs upon filling high Landau levels, it was recently observed a new class of collective states, which can be related to the spontaneous formation of a charge density wave (``striped phase''). We address to the following unsolved problem: what is the reason for stripe pinning along the crystallographic direction [110]? It is shown that in a single heterojunction (001) III-V the effective mass of 2D electrons is anisotropic. T...

In this work we present a theoretical approach to study the effect of an in-plane (parallel) magnetic field on the microwave-assisted transport properties of a two-dimensional electron system. Previous experimental evidences show that microwave-induced resistance oscillations and zero resistance states are differently affected depending on the experimental set-up: two magnetic fields (two-axis magnet) or one tilted magnetic field. In the first case, experiments report a clear...

We report measurements of magneto-resistance commensurability peaks, induced by a square array of anti-dots, in GaAs (311)A two-dimensional holes as a function of applied in-plane strain. The data directly probe the shapes of the Fermi contours of the two spin subbands that are split thanks to the spin-orbit interaction and strain. The experimental results are in quantitative agreement with the predictions of accurate energy band calculations, and reveal that the majority spi...

We investigate the spin dynamics of high-mobility two-dimensional electrons in GaAs/AlGaAs quantum wells grown along the $[001]$ and $[110]$ directions by time-resolved Faraday rotation at low temperatures. In measurements on the $(001)$-grown structures without external magnetic fields, we observe coherent oscillations of the electron spin polarization about the effective spin-orbit field. In non-quantizing magnetic fields applied normal to the sample plane, the cyclotron mo...

The effective Hamiltonian describing the motion of an exciton in an external non-homogeneous magnetic field is derived. The magnetic field plays the role of an effective potential for the exciton motion, results into an increment of the exciton mass and modifies the exciton kinetic energy operator. In contrast to the homogeneous field case, the exciton in a non-homogeneous magnetic field can also be trapped in the low field region and the field gradient increases the exciton ...

We report the observation of an anomalous state of a 2D electron gas near a vicinal surface of a silicon MOSFET in high magnetic fields. It is characterised by unusual behaviour of the conductivities $\sigma_{xx}$ and $\sigma_{xy}$, which can be described as a collapse of the Zeeman spin splitting accompanied by a large peak in $\sigma_{xx}$ and an anomalous peak in $ \sigma_{xy}$. It occurs at densities corresponding to the position of the Fermi level above the onset of the ...