Phonon induced resistance oscillations (PIRO) caused by THz laser

PIRO terms the magneto-resistance (MR) oscillation originating from the resonant interaction of 2D electrons with thermal acoustic phonons [1], observed only in very high mobility samples (>10⁷ cm²V^-1s^-1) [2].
This manifests itself as a 1/B periodic oscillation of the MR of GaAs/AlGaAs heterostructure, in a temperature range of 4-10 K and high filling factors (magnetic fields below 500 mT).
In this work we use THz excitation of the acoustic phonon branch of GaAs by means of a 1.8 THz pulsed quantum cascade laser, so the acoustic phonons are excited by the THz radiation rather than thermally.
Electrons resonantly absorb the acoustic phonons accompanied by a 2 k_F momentum transfer, causing indirect transitions between Landau levels.
The thermally induced PIRO’s are not observable in our samples, probably due to the electron mobility being about a factor of two lower than those given in [2].
[1] M.A. Zudov et al. Phys. Rev. Lett. 86, 3614 (2001).
[2] A. Hatke et al. Phys. Rev. Lett. 102, 086808 (2009).