Resonant Polaron Coupling of High Index Electron Landau Levels in GaAs Heterostructures

The resonant polaron coupling of high index Landau levels was investigated for quasi-two-dimensional electron inversion layers in GaAs. Strong polaron mass enhancements were observed in magnetic field regimes where the Landau levels $N=2\mathrm{}$ and 3 cross with the level $N=0\mathrm{}$ plus one bulk longitudinal optical phonon. The polaron masses were excellently described with a Fröhlich coupling constant $\alpha =0.06\mathrm{}$ to 0.07 taking into account band coupling phenomena, a finite extent of the inversion layer in growth direction, and coupling of the electrical dipole transitions between the Landau levels due to electron-electron interactions.