Excited two-dimensional magnetopolaron states in quantum well of resonant tunnel junction

Tunnel spectroscopy is used to probe the electronic structure in GaAs quantum well of resonant tunnel junction over wide range of energies and magnetic fields normal to layers. Spin degenerated high Landau levels ($N=2div7$) are found to be drastically renormalised near energies when the longitudinal optical-phonon ($hbaromega_{LO}$) and cyclotron energy ($hbaromega_{C}$) are satisfied condition $hbaromega_{LO}=mhbaromega_{C}$, where $m=1,2,3$. This renormalisation is attributed to formation of resonant magnetopolarons, i.e. mixing of high index Landau levels by strong interaction of electrons at Landau level states with LO-phonons.