Interference quantum correction to conductivity of AlxGa1-xAs/GaAs double quantum well heterostructures near the balance

We present the results of experimental investigations of the interference quantum correction to the conductivity of the gated double quantum well AlxGa1-xAs/GaAs/AlxGa1-xAs heterostructures. Analyzing the positive magnetoconductivity we obtain the interwell transition rate and the phase relaxation rate under the conditions when one and two quantum wells are occupied. It has been found that the interwell transition rate resonantly depends on the difference between the electron densities in the wells in accordance with the theoretical estimate. The central point, however, is that the dephasing rate in the lower quantum well is independent of whether the upper quantum well contributes to the conductivity or not. The results obtained are interpreted within framework of the recent theory for the dephasing and electron-electron interaction in the double well structures [Burmistrov I S, Gornyi I V and Tikhonov K S 2011 Phys. Rev. B 84 075338].