Low Temperature Physics: 37, 202 (2011); https://doi.org/10.1063/1.3573648 (8 pages)
Two-dimensional semimetal in HgTe-based quantum wells
Z.D. Kvon1,2, E.B. Olshanetsky1, D.A. Kozlov1, E. Novik3, N.N. Mikhailov1, and S.A. Dvoretsky1
Institute of Semiconductor Physics SB RAS, Novosibirsk 6300090, Russia
2Novosibirsk State University, Novosibirsk 6300090, Russia
3Physikalisches Institut (EP3), University of Wurzburg, 97074 Wurzburg, Germany
Received September 24, 2010
The properties of tow-dimensional semimetal (2DS) in HgTe based quantum wells are described and analyzed. They include: 1) energy spectrum of 2DS and its origin, 2) scattering processes in 2DS, 3) the behaviour of 2DS in a regime of quantum Hall effect particularly in the vicinity of charge neutrality point. On the basis of magnetotransport experiments the value of the overlap was determined. It proves to be equal Δ = (3–5) meV. It is shown that this overlap is due to tensile strain caused by lattice mismatch of HgTe and CdTe. It is shown that impurity scattering prevails in this system at low temperatures. Interparticle scattering (in this case, between electrons and holes) has been observed to directly affect the resistance of the metal. At the charge neutrality point with nearly equal electron and hole densities, the resistance is found to increase very strongly with B while the Hall resistivity turns to zero. This behavior results in a wide plateau in the Hall conductivity and in a minimum of diagonal conductivity. We suggest that the transport at the charge neutrality point is determined by electron–hole snake-like states propagating along the filling factor ν = 0 lines.
PACS: 73.43.Qt Magnetoresistance;
Key words: semimetals, electrons and holes, gapless semiconductors, quantum wells, quantum Hall effect.