Magnetophonon resonance in quantum wells in tilted field. What is   concealed behind its angular dependence?
  Magnetophonon resonance in quantum wells in a tilted magnetic field B is investigated. Measurements of the Hall coefficient and correspondingly of the carrier concentration as a functions of magnetic field and temperature are simultaneously performed. It is shown that the experimental data can be interpreted in terms of a great sensitivity of the effect to the variation of the two dimensional carrier concentration n in a certain concentration interval. In other words, the observed angular dependence of the MPR amplitudes is a manifestation of dependence of n on the magnitude of the magnetic field B. 
V.V.Afonin, V.L.Gurevich, R.Laiho, M.O.Safonchik, M.A.Shakhov, and   M.L.Shubnikov