111 research outputs found
Negative polarizability of 2D electrons in HgTe quantum well
The polarizability of electrons occupying the lowest subband of spatial
quantization in CdTe/CdHgTe/CdTe quantum wells is calculated. It is
shown that polarizability in the quantum well without cadmium is negative,
i.e., the displacement of an electron in an electric field applied
perpendicularly to the quantum well plane is opposite to the force acting on
it. The negative polarizability of 2D electrons can reduce the dielectric
constant of quantum wells by up to percent.Comment: 4 pages, 4 figure
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]
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