We propose to use phonon absorption spectroscopy to study many-body gaps and phases of two-subband heterostructures in the quantum Hall regime. Implications of the spin-orbit interaction for phonon absorption in this system are considered.
@article{arxiv.cond-mat/0301330,
title = {Probing two-subband systems in a quantizing magnetic field with non-equilibrium phonons},
author = {M. E. Portnoi and K. V. Kavokin and V. M. Apalkov},
journal= {arXiv preprint arXiv:cond-mat/0301330},
year = {2007}
}