We report a detailed study of the transport coefficients of β-Bi4I4 quasi-one dimensional topological insulator. Electrical resistivity, thermoelectric power, thermal conductivity and Hall coefficient measurements are consistent with the possible appearance of a charge density wave order at low temperatures. Both electrons and holes contribute to the conduction in β-Bi4I4 and the dominant type of charge carrier changes with temperature as a consequence of temperature-dependent carrier densities and mobilities. Measurements of resistivity and Seebeck coefficient under hydrostatic pressure up to 2 GPa show a shift of the charge density wave order to higher temperatures suggesting a strongly one-dimensional character at ambient pressure. Surprisingly, superconductivity is induced in β-Bi4I4 above 10 GPa with of 4.0 K which is slightly decreasing upon increasing the pressure up to 20 GPa. Chemical characterisation of the pressure-treated samples shows amorphization of β-Bi4I4 under pressure and rules out decomposition into Bi and BiI3 at room-temperature conditions.
@article{arxiv.1702.04794,
title = {Pressure effect and Superconductivity in $\beta$-Bi$_4$I$_4$ Topological Insulator},
author = {A. Pisoni and R. Gaal and A. Zeugner and V. Falkowski and A. Isaeva and H. Huppertz and G. Autes and O. V. Yazyev and L. Forro},
journal= {arXiv preprint arXiv:1702.04794},
year = {2017}
}