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2DEG; microwaves; zero-resistance states; Landau levels
Abstract:
Microwave induced resistance oscillations (MIROs) were studied
experimentally over a very wide range of frequencies ranging from
similar to 20 GHz up to similar to 4 THz, and from the quasi-classical
regime to the quantum Hall effect regime. At low frequencies regular
MIROs were observed, with a periodicity determined by the ratio of the
microwave to cyclotron frequencies. For frequencies below 150 GHz the
magnetic field dependence of MIROs waveform is well described by a
simplified version of an existing theoretical model, where the damping
is controlled by the width of the Landau levels. In the THz frequency
range MIROs vanish and only pronounced resistance changes are observed
at the cyclotron resonance. The evolution of MIROs with frequency is
presented and discussed. (c) 2006 Elsevier B.V. All rights reserved.