We report on the observation of the quantum Hall effect at high temperatures in HgTe quantum wells with a finite band gap and a thickness below and above the critical thickness dc that separates a conventional semiconductor from a two-dimensional topological insulator. At high carrier concentrations we observe a quantized Hall conductivity up to 60\,K with energy gaps between Landau Levels of the order of 25\,meV, in good agreement with the Landau Level spectrum obtained from k⋅p-calculations. Using the scaling approach for the plateau-plateau transition at ν=2→1, we find the scaling coefficient κ=0.45±0.04 to be consistent with the universality of scaling theory and we do not find signs of increased electron-phonon interaction to alter the scaling even at these elevated temperatures. Comparing the high temperature limit of the quantized Hall resistance in HgTe quantum wells with a finite band gap with room temperature experiment in graphene, we find the energy gaps at the break-down of the quantization to exceed the thermal energy by the same order of magnitude.
@article{arxiv.1605.03342,
title = {High-temperature quantum Hall effect in finite gapped HgTe quantum wells},
author = {T. Khouri and M. Bendias and P. Leubner and C. Brüne and H. Buhmann and L. W. Molenkamp and U. Zeitler and N. E. Hussey and S. Wiedmann},
journal= {arXiv preprint arXiv:1605.03342},
year = {2016}
}