Magnetic oscillations of microwave transmission in a quantum well with two populated subbands

The transmission of microwave radiation at a frequency of $125$ GHz through a two-subband electron system in a GaAs quantum well at the temperature $T = 4.2$ K in magnetic fields $B < 1$ T has been studied. Oscillations with the period determined by the ratio of the intersubband splitting energy to the cyclotron energy have been found in the magnetic field dependence of the transmitted microwave power. The obtained experimental data are in qualitative agreement with the theory of the ac conductivity of quantum wells with two populated quantum-confinement subbands (O.E. Raichev, Phys. Rev. B 78, 125304 (2008)).