Transport equation for 2D electron liquid under microwave radiation plus   magnetic field and the Zero Resistance State
  A general transport equation for the center of mass motion is constructed to study transports of electronic system under uniform magnetic field and microwave radiation. The equation is applied to study 2D electron system in the limit of weak disorder where negative resistance instability is observed when the radiation field is strong enough. A solution of the transport equation with spontaneous AC current is proposed to explain the experimentally observed Radiation-Induced Zero Resistance State. 
Tai-Kai Ng and Lixin Dai