Magnetophonon resonance of a two-dimensional electron gas in a quantum well

Magnetophonon resonance of the transverse magnetoresistance is investigated theoretically and experimentally in AlGaAs/GaAs/AlGaAs quantum wells. The interaction Hamiltonian of the two-dimensional electron gas (2DEG) is derived for the scattering by the LO phonons confined in the quantum wells, which reveals that the inter-sub-band transition of the 2DEG plays an important role in the magnetophonon resonance. The authors evaluated the magnetoconductivity of the 2DEG in a quantum well using the Kubo formula. The calculated magnetoresistance exhibits oscillations arising from both the intra-sub-band and inter-sub-band transitions of the 2DEG induced by the scattering of confined LO phonon, resulting in the periods of oscillations in reciprocal magnetic fields, 24 and 41 T, which are in good agreement with the present observation in an AlGaAs/GaAs/AlGaAs quantum well with a GaAs well width of 100 AA (24 and 45 T). The present results indicate that the magnetophonon resonance in a quantum well arises from the scattering of the 2DEG by the LO phonons whose mode is confined in the well region.