Electronic structure, galvanomagnetic and magnetic properties of the bismuth subhalides Bi4I4 and Bi4Br4

• Two bismuth-rich subhalides, Bi4Br4 and Bi4I4, 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 Bi4Br4 demonstrates a typical case of one dimensionality, the difference in magnetoresistivity between Bi4Br4 and Bi4I4 indicates some weak interactions between isolated bismuth metallic fragments within the bismuth substructures.

Nyckelord

bismuth-rich compounds

subhalides

low-dimensional structures

electronic structure

conductivity

magnetic properties

crystal-structure

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