In a pressure-temperature $\left(P\text{−}T\right)$ diagram for synthesizing $\mathrm{IrT}{\mathrm{e}}_2$ compounds, the well-studied trigonal $\left(H\right)$ phase with the $\mathrm{Cd}{\mathrm{I}}_2$-type structure is stable at low pressures. The superconducting cubic $\left(C\right)$ phase can be synthesized under higher temperatures and pressures. A rhombohedral phase with the crystal structure similar to the $C$ phase can be made at ambient pressure; but the phase contains a high concentration of Ir deficiency. In this paper we report that a rarely studied monoclinic $\left(M\right)$ phase can be stabilized in narrow ranges of pressure and temperature in this $P\text{−}T$ diagram. The peculiar crystal structure of the $M\text{−}\mathrm{IrT}{\mathrm{e}}_2$ eliminates the tendency to form Ir-Ir dimers found in the $H$ phase. The $M$ phase has been fully characterized by structural determination and measurements of electrical resistivity, thermoelectric power, DC magnetization, and specific heat. These physical properties have been compared with those in the $H$ and $C$ phases of $\mathrm{I}{\mathrm{r}}_{1-x}\mathrm{T}{\mathrm{e}}_2$. Moreover, magnetic and transport properties and specific heat of the $M\text{−}\mathrm{IrT}{\mathrm{e}}_2$ can be fully justified by calculations with the density-functional theory presented in this paper.

• Received 11 May 2015
• Revised 19 September 2015

DOI:https://doi.org/10.1103/PhysRevB.92.155118