The paper presents experimental results of the appearance of a voltage at the potential contacts in the absence of an external current through a sample in the plateau region of the quantum Hall effect in a heterostructure with an InGaAs/InAlAs quantum well. The occurrence of a voltage is associated with the nonequivalence of the edge current in the potential contact areas in a magnetic field in a system with a two-dimensional electron gas.

The effects observed in the Shubnikov–de Haas oscillation regime in the HgCdTe/HgTe/HgCdTe heterostructure with a wide (20.3 nm) HgTe quantum well with an inverted band structure are discussed. In a topologically trivial 2D system, a π-shift of magnetooscillation phase is found. A thorough experimental study and theoretical analysis of the data is presented to understand the physical causes of this anomalous phase shift. The effective electron mass m c / m 0 = (0.022 ± 0.002) obtained from the region of doubly degenerate magnetoresistance peaks is approximately half the theoretical estimates. In the region of stronger magnetic fields, for non-degenerate magnetoresistance peaks, we have m c / m 0 = (0.034 ± 0.003), which is in good agreement with both theoretical predictions and experimental results obtained from the analysis of activation conductivity in the quantum Hall effect regime. The reasons for this discrepancy are discussed.

Quasiclassical calculations of the effective cyclotron mass and the spectrum of Landau levels have been carried out for carriers of the size-quantized H2 subband with a nonmonotonic dispersion law, which forms a valence band of 20.5-nm-wide HgTe quantum well with an inverted band structure. The model of the so-called “extremum loop”, previously developed by Rashba and Sheka for semiconductors with a wurtzite lattice, has been used for calculations. The results obtained are compared both with the empirical picture and with quantum-mechanical calculations of the Landau level spectrum for the HgTe quantum well in the semimetallic phase.

The effects observed in the Shubnikov - de Haas oscillation regime in the HgCdTe/HgTe/HgCdTe heterostructure with a wide (20.3 nm) HgTe quantum well with an inverted band structure are discussed. In a topologically trivial 2D system, Pi(Greek letter) - shift of magnetooscillation phase is found. A thorough experimental study and theoretical analysis of the data is presented to understand the physical causes of this anomalous phase shift. The value of the effective electron mass m_c/m_0 = (0.022+-0.002), obtained from the region of doubly degenerate peaks of magnetoresistance, is approximately half the theoretical estimates. In the region of stronger magnetic fields for nondegenerate peaks of magnetoresistance, we have m_c/m_0 = (0.034+-0.003), which is in good agreement with both theoretical predictions and experimental results obtained from the analysis of activation conductivity in the quantum Hall effect regime. The reasons for this discrepancy are discussed.

The results of the longitudinal and Hall magnetoresistivity measurements in the Shubnikov - de Haas oscillation regime for the HgCdTe/HgTe/HgCdTe heterostructures with a wide (20.3 nm) HgTe quantum well are presented. An anomalous phase shift of magneto-oscillations is detected: in the region of spin-unsplit peaks the longitudinal resistivity maxima are located at even filling factor numbers in contradiction with a conventional situation in 2D systems. It is shown that the observed features are associated with the inverted nature of the spectrum in the investigated quantum well with the electron-type conduction along the size-quantized subband H1 of HgTe band {\Gamma}8, for which the spin splitting is comparable to (and even greater than) the orbital one. The results obtained are compared with the phase shift effects of both magneto-oscillations and the plateau of the quantum Hall effect in monolayer graphene.

We present a study of Shubnikov–de Haas (SdH) oscillations at temperatures of (2.2–10) K in magnetic fields up to 2.5 T in the HgCdTe/HgTe/HgCdTe heterostructure for a wide (20.3 nm) HgTe quantum well with an inverted energy band structure. The analysis of the temperature dependence of SdH amplitude in weak fields, in a region of doubly degenerate magnetoresistance peaks, led us to the value of effective electron mass mc/m0 = (0.022 ± 0.002) which is about half the theoretical estimates. But in a region of higher magnetic fields, for nondegenerate magnetoresistance peaks, we confidently have mc/m0 = (0.034 ± 0.003) in good agreement both with the theoretical estimation and with our experimental results on the analysis of activation transport under quantum Hall effect regime. The reasons for this discrepancy are discussed.