Cyclotron and combined phonon-assisted resonances in double-well heterostructure In$_{0.65}$Ga$_{0.35}$As/In$_{0.52}$Al$_{0.48}$As at megagauss magnetic fields.

Experiments on resonances of conduction electrons in InGaAs/InAlAs double quantum wells at megagauss magnetic fields in the Faraday geometry are reported. We observe new cyclotron resonances assisted by emission of InAs-like and GaAs-like optic phonons and a combined (cyclotron-spin) resonance assisted by emission of InAs-like phonon. The observations are very well described for three laser frequencies with the use of an eight-band (three level) $\textbf{k}\cdot \textbf{p}$ model, taking into account position- and energy-dependent effective masses and spin g-factors. It is indicated that the new observations are possible due to the application very high magnetic fields.