189 research outputs found
Weak localization in macroscopically inhomogeneous two-dimensional systems: a simulation approach
A weak-localization effect has been studied in macroscopically inhomogeneous
2D system. It is shown, that although the real phase breaking length tends to
infinity when the temperature tends to zero, such a system can reveal a
saturated behavior of the temperature dependence of that parameter, which is
obtained from the standard analysis of the negative magnetoresistance and
usually identified by experimentalists with the phase braking length.Comment: 5 pages, 4 figure
Interference quantum correction to conductivity of Al xGa 1-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 Al xGa 1-xAs/GaAs/Al xGa 1-xAs heterostructures. Analyzing the positive magnetoconductiv-ity 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]
Two-dimensional semimetal in a wide HgTe quantum well: magnetotransport and energy spectrum
The results of experimental study of the magnetoresistivity, the Hall and
Shubnikov-de Haas effects for the heterostructure with HgTe quantum well of
20.2 nm width are reported. The measurements were performed on the gated
samples over the wide range of electron and hole densities including vicinity
of a charge neutrality point. Analyzing the data we conclude that the energy
spectrum is drastically different from that calculated in framework of
-model. So, the hole effective mass is equal to approximately and
practically independent of the quasimomentum () up to cm, while the theory predicts negative (electron-like)
effective mass up to cm. The experimental
effective mass near k=0, where the hole energy spectrum is electron-like, is
close to , whereas the theoretical value is about
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