Cyclotron resonance absorption of 2D holes in strained InGaAs/GaAs quantum wells under high magnetic fields

We report a systematic study of the cyclotron resonance (CR) absorption of two dimensional (2D) holes in strained InGaAs/GaAs quantum wells (QWs) in the quantum limit. The energies of CR transitions are traced as a function of magnetic field up to 55 T. A remarkable CR line splitting was evidenced when the resonant field exceeds 20 T. We analyze our date with a 4x4 Luttinger Hamiltonian including strain and QW potentials and find excellent agreement in the positions of the resonances. On the other hand, the spectral weight distribution of the split components suggests an inverted position of the two first Landau levels compared to the theoretical model.