Anionic depolymerization transition in IrTe2

Abstract

Selenium (Se) substitution drastically increases the transition temperature of iridium ditelluride (IrTe${}_2$) to a diamagnetic superstructure from 278 K to 560 K. Transmission electron microscopy experiments revealed that this enhancement is accompanied by the evolution of non-sinusoidal structure modulations from $q=1/5(10\bar{1})$- to $q=1/6(10\bar{1})$-types. These comprehensive results are consistent with the concept of the destabilization of polymeric Te-Te bonds at the transition, the temperature of which is increased by chemical and hydrostatic pressure and by the substitution of Te with the more electronegative Se. This temperature-induced depolymerization transition in IrTe${}_2$ is unique in crystalline inorganic solids.

5 pages, 4 figures, Phys. Rev. Lett. in press