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We report on observation of an unconventional structure of the quantum Hall effect (QHE) in a $ p$-type HgTe/Cd$_x$Hg$_{1-x}$Te double quantum well (DQW) consisting of two HgTe layers of critical width. The observed QHE is a reentrant function of magnetic field between two $i=2$ states (plateaus at $rho_{xy}=h/ie^2$) separated by an intermediate $i=1$ state, which looks like some anomalous peak on the extra-long $i=2$ plateau when weakly expressed. The anomalous peak apparently separates two different regimes: a traditional QHE at relatively weak fields for a small density of mobile holes $p_s$ and a high-field QH structure with a $2-1$ plateau--plateau transition corresponding to much larger $p_s$. We show that only a part of holes, residing in an additional light hole subband in the DQW, participate in QHE at weak fields while the rest of holes is excluded into the reservoir formed in the lateral maximum of the valence subband. All the holes come into play at high fields due to a peculiar behavior of the zero-mode levels.
We describe the observation of the circular and linear photogalvanic effects in HgTe/CdHgTe quantum wells. The interband absorption of mid-infrared radiation as well as the intrasubband absorption of terahertz (THz) radiation in the QWs structures is
We calculate the characteristics of interband HgTe-CdHgTe quantum-well infrared photodetectors (QWIPs). Due to a small probability of the electron capture into the QWs, the interband HgTe-CdHgTe QWIPs can exhibit very high photoconductive gain. Our a
Magnetotransport measurements are presented on paramagnetic (Hg,Mn)Te quantum wells (QWs) with an inverted band structure. Gate-voltage controlled density dependent measurements reveal an unusual behavior in the transition regime from n- to p-type co
The two-dimensional topological insulator phase has been observed previously in single HgTe-based quantum wells with inverted subband ordering. In double quantum wells (DQWs), coupling between the layers introduces additional degrees of freedom leadi
We report on the observation of the quantum Hall effect at high temperatures in HgTe quantum wells with a finite band gap and a thickness below and above the critical thickness $d_textnormal{c}$ that separates a conventional semiconductor from a two-