|Temperature-driven single-valley Dirac fermions in HgTe quantum wells |
Auteur(s): Marcinkiewicz M., Ruffenach S., Krishtopenko S., Kadykov A., Consejo C., But D., Desrat W., Knap W., Torres J., Ikonnikov A. V., Spirin K. E., Morozov S. V., Gavrilenko V. I., Mikhailov N. N., Dvoretskii S. A., Teppe F.
Ref HAL: hal-01583239_v1
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We report on the temperature-dependent magnetospectroscopy of two HgTe/CdHgTe quantum wells below and above the critical well thickness dc. Our results, obtained in magnetic fields up to 16 T and s temperature range from 2 to 150 K, clearly indicate a change in the band-gap energy with temperature. A quantum well wider than dc evidences a temperature-driven transition from topological insulator to semiconductor phases. At a critical temperature of 90 K, the merging of inter- and intraband transitions in weak magnetic fields clearly specifies the formation of a gapless state, revealing the appearance of single-valley massless Dirac fermions with a velocity of 5.6×105ms−1. For both quantum wells, the energies extracted from the experimental data are in good agreement with calculations on the basis of the eight-band Kane Hamiltonian with temperature-dependent parameters.