Magneto-resistance oscillations and zero-resistance states induced by photo-excitation in the quasi two-dimensional GaAs/AlGaAs system

Photo-excitation of high quality two dimensional electron systems induces "1/4 cycle shifted" inverse- B-periodic magnetoresistance oscillations with nodes in the resistance at B_f / j for the fundamental series, where j is a positive integer or half integer, B_f is the characteristic magnetic field that increases with the radiation frequency, f, as B_f = 2pi f m*/e, m* is an electron effective mass, and e is the electron charge. At the lowest temperatures and modest magnetic fields, vanishing diagonal resistance is observed at the resistance minima as in the quantum Hall situation, without concomitant plateaus in the Hall effect. Here, we describe and review the remarkable features of these novel effects.