Shubnikov–de Haas-like oscillations in millimeterwave photoconductivity in a high-mobility two-dimensional electron gas

Abstract

Millimeterwave photoconductivity in a high-mobility $\mathrm{GaAs}\ensuremath{-}{\mathrm{Al}}_{x}{\mathrm{Ga}}_{1\ensuremath{-}x}\mathrm{As}$ two-dimensional electron gas exhibits giant amplitude oscillations in a weak magnetic field. These oscillations resemble the Shubnikov--de Haas effect but their period is determined by $\ensuremath{\omega}/{\ensuremath{\omega}}_{C},$ where $\ensuremath{\omega}$ and ${\ensuremath{\omega}}_{C}$ are the millimeterwave and cyclotron frequencies, respectively. The major observations can be explained in terms of Landau-level transitions between spatially shifted oscillators. A ${2k}_{F}$ momentum transfer is accompanying the transition where ${k}_{F}$ is the electron Fermi wave number.