Magnetotransport in Double Quantum Well with Inverted Energy Spectrum: HgTe/CdHgTe

Abstract

We present the first experimental study of the double-quantum-well (DQW) system made of 2D layers with inverted energy band spectrum: HgTe. The magnetotransport reveals a considerably larger overlap of the conduction and valence subbands than in known HgTe single quantum wells (QW), which may be regulated by an applied gate voltage $V_g$. This large overlap manifests itself in a much higher critical field $B_c$ separating the range above it where the quantum peculiarities shift linearly with $V_g$ and the range below with a complicated behavior. In the latter case the $N$-shaped and double-$N$-shaped structures in the Hall magnetoresistance ${\rho }_{xy}(B)$ are observed with their scale in field pronouncedly enlarged as compared to the pictures observed in an analogous single QW. The coexisting electrons and holes were found in the whole investigated range of positive and negative $V_g$ as revealed from fits to the low-field $N$-shaped ${\rho }_{xy}(B)$ and from the Fourier analysis of oscillations in ${\rho }_{xx}(B)$. A peculiar feature here is that the found electron density $n$ remains almost constant in the whole range of investigated $V_g$ while the hole density $p$ drops down from the value a factor of 6 larger than $n$ at extreme negative $V_g$ to almost zero at extreme positive $V_g$ passing through the charge neutrality point. We show that this difference between $n$ and $p$ stems from an order of magnitude larger density of states for holes in the lateral valence band maxima than for electrons in the conduction band minimum. We interpret the observed reentrant sign-alternating ${\rho }_{xy}(B)$ between electronic and hole conductivities and its zero resistivity state in the quantum Hall range of fields on the basis of a calculated picture of magnetic levels in a DQW.

15 pages, 13 figures

References in corpus (8)

• Quantum Spin Hall Insulator State in HgTe Quantum Wells
• The Quantum Spin Hall Effect: Theory and Experiment
• Landau Level Splitting in Graphene in High Magnetic Fields
• Fine structure of "zero-mode" Landau levels in HgTe/HgCdTe quantum wells
• Devices with electrically tunable topological insulating phases
• Nonlocal transport near the charge neutrality point in a two-dimensional electron-hole system
• Optical manipulation of edge state transport in HgTe quantum wells in the quantum hall regime
• Unconventional Hall effect near charge neutrality point in a two-dimensional electron-hole system

Cited by in corpus (4)

• Magnetoresistance of compensated semimetals in confined geometries
• Unconventional Reentrant Quantum Hall Effect in a HgTe/CdHgTe Double Quantum Well
• Quantum capacitance of an HgTe quantum well as an indicator of the topological phase
• Double valley Dirac fermions for 3D and 2D Hg${}_{1-x}$Cd${}_x$Te with strong asymmetry