Observation of electron spin resonance in the microwave-induced photovoltage

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.