  Recent experimental results regarding a 2D electron gas subjected to
microwave radiation reveal that magnetoresistivity, apart from presenting
oscillations and zero resistance states, can evolve to negative values at
minima. In other words, the current can evolve from flowing with no
dissipation, to flow in the opposite direction of the dc bias applied. Here we
present a theoretical model in which the existence of radiation-induced
absolute negative conductivity is analyzed. Our model explains the transition
from zero resistance states to absolute negative conductivity in terms of
multiphoton assisted electron scattering due to charged impurities. It shows as
well, how this transition can be driven by tuning microwave frequency and
intensity. Then it opens the possibility of controlling the electron Larmor
orbits dynamics (magnetoconductivity) in microwave driven nanodevices. The
analysis of zero resistance states is therefore promising because new optical
and transport properties in nanodevices will be expected.
