Probing the coexistence of semiclassical transport and localization in a two-dimensional electron gas using microwave radiation

We have performed magnetoresistance measurements on a GaAs/AlGaAs two-dimensional electron gas under microwave heating. Both the magneto-oscillations and magnetoresistance minima are used as electron thermometers to determine the electron effective temperature Te. When there is no clear cyclotron gap, it is found that Te determined from these two methods can be substantially different such that we can still distinguish localized electrons from the semiclassical conducting ones. The almost constant Te obtained from the magnetoresistance minima reveals the survived equivalence between different Landau-band tails under insufficient localization.