Switching of Conducting Planes by Partial Dimer Formation in IrTe${}_2$

Abstract

Single-crystal X-ray diffraction was employed to study the structural-electronic phase transition of IrTe${}_2$ at approximately 270 K. The low-temperature structure was found to be a triclinic (space group $P\bar{1}$) characterized by the partial formation of Ir${}_2$ dimers in the triangular lattice of IrTe${}_2$, resulting in a structural modulation with a wave vector of $\mathbf{q}=(1/5,0,-1/5)$. First-principles band calculations demonstrate that tilted two-dimensional Fermi surfaces emerge in the triclinic phase, suggesting that switching of the conducting planes occurs from the basal plane of the trigonal IrTe${}_2$ to the tilted plane normal to $\mathbf{q}$ of the triclinic IrTe${}_2$.

5 pages, 4 figures. Supplemental Material will be sent you upon request