Memory effects in ac hopping conductance in the quantum Hall effect regime: Possible manifestation of DX${}^{-}$ centers

I. L. Drichko, A. M. Diakonov, I. Yu. Smirnov +3

Using simultaneous measurements of the attenuation and velocity of surface acoustic waves propagating along GaAs/Al${}_{0.3}$Ga${}_{0.7}$As heterostructures, complex ac conductance of…