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The microwave-induced photovoltage in two-dimensional electron systems in an AlAs quantum well and a ZnO/MgZnO heterojunction under the conditions of the quantum Hall effect is investigated. When the magnetic field is varied smoothly at a fixed microwave frequency, a sharp peak corresponding to the spin resonance of two-dimensional conduction electrons occurs in the recorded photovoltage. This is the first observation of spin resonance in two-dimensional electron systems by such a technique. It is demonstrated that this technique can be used both with the Hall bar and Corbino disk configurations of the ohmic contacts to the two-dimensional channel despite the essential difference between these configurations. This technique is compared with the conventional technique for the detection of spin resonance in a two-dimensional electron system by measuring the change in the resistance caused by the absorption of microwave radiation. [ABSTRACT FROM AUTHOR]

Microwave-induced magnetoresistance and magnetoconductance oscillations in the two-dimensional electron system have been detected in a ZnO/MgZnO heterojunction. The structure has a high electron density of n = 6.5 × 10 cm and a very low mobility of 10 cm V s. This clearly indicates that the mobility of two-dimensional electrons is not a critical parameter for the observation of microwave-induced oscillations. The samples were both Hall bars and Corbino disks. At least four oscillations have been resolved. Their amplitude increases with the magnetic field and all oscillations with numbers >1 have the same phase of 0.25. It has been shown that the microwave-induced photoelectromotive force is also a periodically oscillating function of the inverse magnetic field. [ABSTRACT FROM AUTHOR]

Electron spin resonance in GaAs/AlGaAs quantum wells in the vicinity of odd filling factors ν = 3, 5, and 7 is investigated. The spin relaxation time of two-dimensional electrons is determined from the width of the microwave resonance absorption line. Dependences of the spin relaxation time on the filling factor, temperature, and orientation of the magnetic field are investigated. The spin relaxation time decreases noticeably upon deviation from odd filling factors, and its maximum value depends on the angle between the magnetic field and the plane of the two-dimensional electron gas. [ABSTRACT FROM AUTHOR]

The anisotropy of electron g-factor is investigated for several GaAs/AlxGa1-xAs heterostructures using an electrically detected electron spin resonance technique at liquid helium temperature. For a modulation-doped 25-nm single quantum well with electron density n=4×1011 cm-2 we extracted an out-of-plane g-factor value of ∣gzz∣=0.410 and in-plane values of ∣gyy∣=0.359 and ∣gxx∣=0.289. In addition, linear in magnetic field corrections to the g-factor components were also extracted and strong anisotropy in their values was established. [ABSTRACT FROM AUTHOR]

The magnetic field dependence of the cyclotron mass of heavy holes in asymmetric GaAs(100) quantum wells is measured by optical detection of resonant microwave absorption for various concentrations of quasi-two-dimensional holes. The effect of spin-orbit splitting on the cyclotron masses of heavy holes is discovered and investigated. The energy spectrum of holes is calculated on the basis of experimental data. The energy range in which spin-plasmon oscillations are observed in hole systems with various concentrations is predicted. [ABSTRACT FROM AUTHOR]