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arXiv · 1702.06869

Temperature-driven single-valley Dirac fermions in HgTe quantum wells

M. Marcinkiewicz·S. Ruffenach·S. S. Krishtopenko·A. M. Kadykov·C. Consejo·D. B. But·W. Desrat·W. Knap·J. Torres·A. V. Ikonnikov·K. E. Spirin·S. V. Morozov·V. I. Gavrilenko·N. N. Mikhailov·S. A. Dvoretskii·F. Teppe
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Abstract

We report on temperature-dependent magnetospectroscopy of two HgTe/CdHgTe quantum wells below and above the critical well thickness $d_c$. Our results, obtained in magnetic fields up to 16 T and temperature range from 2 K to 150 K, clearly indicate a change of the band-gap energy with temperature. The quantum well wider than $d_c$ evidences a temperature-driven transition from topological insulator to semiconductor phases. At the critical temperature of 90 K, the merging of inter- and intra-band transitions in weak magnetic fields clearly specifies the formation of gapless state, revealing the appearance of single-valley massless Dirac fermions with velocity of $5.6\times10^5$ m$\times$s$^{-1}$. For both quantum wells, the energies extracted from experimental data are in good agreement with calculations on the basis of the 8-band Kane Hamiltonian with temperature-dependent parameters.

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M. Marcinkiewicz, S. Ruffenach, S. S. Krishtopenko, A. M. Kadykov, C. Consejo, D. B. But, W. Desrat, W. Knap, J. Torres, A. V. Ikonnikov, K. E. Spirin, S. V. Morozov, V. I. Gavrilenko, N. N. Mikhailov, S. A. Dvoretskii, F. Teppe. 2017-02-22. Temperature-driven single-valley Dirac fermions in HgTe quantum wells. https://doi.org/10.1103/physrevb.96.035405

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