Switching of Conducting Planes by Partial Dimer Formation in IrTe 2

Single-crystal X-ray diffraction was employed to study the structural-electronic phase transition of IrTe2 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 Ir2 dimers in the triangular lattice of IrTe2, resulting in a structural modulation with a wave vector of 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 IrTe2 to the tilted plane normal to q of the triclinic IrTe2.