Novel structural phases and superconductivity of iridium telluride under high pressures.

Transition metal selenide and telluride have recently receive considerable attention due to their possible structural relation to ferropnictide. Pressure is often used as an efficient way to modify the crystal or electronic structure that in many cases lead to new material states of interest. Here we search the structures of IrTe2 up to 150 GPa using crystal structure prediction techniques combining with ab initio calculations. Three new stable phases under high pressures are predicted, and their electronic structure properties, phonon spectra, and electron-phonon couplings are also investigated. Significant reconstructions of band structures and Fermi surfaces are found in these new phases. Calculated results show that while the C2/m-2 phase has bad metal behavior and very weak electron-phonon coupling, the and I4/mmm phases have relatively higher electron-phonon coupling up to ~ 1.5 and 0.7, respectively. The variable-composition searching have been performed, newly compounds with different stoichiometries, such as IrTe3, IrTe, and Ir3Te, are predicted to be thermodynamically and dynamically stable at high pressures. The pressure range investigated here is accessible in the diamond anvil cell experiments, thus our results might stimulate further experimental studies.