Visualizing the effect of structural supermodulation on electronic structure of IrTe_2 by scanning tunneling spectroscopy

摘要

We report on the scanning tunneling spectroscopy experiments on single crystals of IrTe_2. A structural supermodulation and a local density-of-states (LDOS) modulation with a wave vector of q = 1/5 × 2π/a_0 (a_0 is the lattice constant in the ab plane) have been observed at 4.2 K, where the sample is in the monoclinic phase. As synchronized with the supermodulation, the LDOS spatially modulates within two energy ranges (below -200 meV and around -100 meV). We further investigated the effect of the local perturbations including the antiphase boundaries and the twin boundaries on the LDOS. These perturbations also modify the LDOS below -200 meV and around -100 meV, even though the lattice distortions induced by these perturbations appear to be different from those by the supermodulation. Our results indicating several microscopic structural effects on the LDOS seem to offer crucial keys for the establishment of the microscopic model describing the parent state.