Electronic structure, galvanomagnetic and magnetic properties of the bismuth subhalides Bi{sub 4}I{sub 4} and Bi{sub 4}Br{sub 4}

Two bismuth-rich subhalides, Bi{sub 4}Br{sub 4} and Bi{sub 4}I{sub 4}, featuring extended quasi one-dimensional metallic fragments in their structures, have been investigated. The gas-phase technique of crystal growth has been refined for obtaining large (up to 5 mm long) single crystals. Electronic structure calculations on three-dimensional structures of both compounds have been performed (DFT level, hybrid B3LYP functional), predicting a semiconducting behavior for both compounds, with an indication of possible directional anisotropy of electric conductivity. Galvanomagnetic (resistance, magnetoresistance, Hall effect, thermopower) and magnetic (temperature and field dependence of magnetization) properties have been measured experimentally. Both compounds are found to be diamagnetic, room-temperature semiconductors with n-type conductivity. While Bi{sub 4}Br{sub 4} demonstrates a typical case of one dimensionality, the difference in magnetoresistivity between Bi{sub 4}Br{sub 4} and Bi{sub 4}I{sub 4} indicates some weak interactions between isolated bismuth metallic fragments within the bismuth substructures. - Graphical abstract: Quasi one-dimensional compounds Bi{sub 4}Br{sub 4} and Bi{sub 4}I{sub 4} have been investigated theoretically (electronic structure calculations) and experimentally (galvanomagnetic and magnetic measurements). Both compounds are found to be diamagnetic, room-temperature semiconductors with n-type conductivity and a possibility of significant directional anisotropy. Magnetoresistivity data indicate some weak interactions between isolated bismuth fragments in Bi{sub 4}I{sub 4}.