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Issue 13, 2018
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Origin of the temperature dependence of the energy gap in Cr-doped Bi2Se3

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Abstract

Recent progress in impurity-doped topological insulators has shown that the gap at the Dirac point shrinks with reducing temperature. This is an obstacle for experimental realization of the quantum anomalous Hall effect at higher temperature due to the requirement of a larger energy gap. In order to solve this puzzle, we study the gap at the Dirac point by performing temperature-dependent photoemission spectroscopy and X-ray diffraction experiments in Cr-doped Bi2Se3. Our valence band photoemission study revealed that the gap alters with temperature due to residual gas condensation on the sample surface with cooling. Residual gas on the sample surface creates an electron doping effect that modifies the chemical potential of the system resulting in the change of the gap size with variable temperature. Furthermore, such electron doping can weaken the ferromagnetism and lead to a bulk band contribution in the transport measurements. Therefore, such effects can hinder the existence of the quantum anomalous Hall state at higher temperatures. Hence, this work can pave the way for future studies towards a high-temperature quantum anomalous Hall effect.

Graphical abstract: Origin of the temperature dependence of the energy gap in Cr-doped Bi2Se3

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Publication details

The article was received on 30 Nov 2017, accepted on 24 Feb 2018 and first published on 26 Feb 2018


Article type: Paper
DOI: 10.1039/C7CP08049B
Citation: Phys. Chem. Chem. Phys., 2018,20, 8624-8628
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    Origin of the temperature dependence of the energy gap in Cr-doped Bi2Se3

    T. Yilmaz, W. Hines, S. Alraddadi, J. I. Budnick and B. Sinkovic, Phys. Chem. Chem. Phys., 2018, 20, 8624
    DOI: 10.1039/C7CP08049B

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