Visualizing the effect of structural supermodulation on electronic structure ofIrTe2by scanning tunneling spectroscopy

Abstract

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.

Nanoscale Superconducting Honeycomb Charge Order in IrTe2

“…In this study, we identify with STM a unprecedented honeycomb charge ordering in nanoscale coexistence with stripe charge orders of IrTe2 [19][20][21][22][23][24] , which is distinct from the hexagonal CDW.…”

“…IrTe2 is currently under extensive investigations due to its unusual electronic properties related to the charge ordering. IrTe2 is an outstanding transition metal dichalcogenide with a charge order (Ir 5d 3+ -Ir 5d 4+ ) transition into 4 stripe phases with a large hysteresis and a nontrivial remnant metallic conductivity [19][20][21][22][23]25,26 .…”

“…1e) [21][22][23] . In extra, we find another distinct phase with a hexagonal symmetry as enclosed by stripe phases of three different orientations on the surface below the transition temperature.…”

Structural versus electronic distortions inIrTe2with broken symmetry

“…Indeed, the recently observed superconductivity of Pt-or Pd-doped IrTe 2 was suspected as being non-conventional or topological [13,14] but a very recent scanning tunneling spectroscopy (STS) study showed the conventional s-wave pairing behavior [15]. While further investigations are called for the nature of the superconductivity, the experimental evidence has been accumulated to indicate the unusual nature of the CDW-like phase transition (T c ≈ 260 K without doping) with a wave vector of (1/5, 0, 1/5) (the ×5 phase, hereafter) [16]. Most importantly, the band gap opening does not occur but the strong restructuring of Fermi surfaces and band structures exists [17][18][19].…”

Bond competition and phase evolution on the IrTe2 surface

“…Both the HT and LT phases of IrTe 2 show significant threedimensional electronic structures reflecting interactions (and in the case of the LT phase, bonding) between adjacent CdI 2 structure layers, which is very different from most layered dichalcogenides, which are generally more two dimensional and show real CDW instabilities 10 . Several scanning tunnelling microscope (STM) studies 11,12 have been reported recently on IrTe 2 , but the relationship between the structural and electronic properties remains to be fully elucidated. In any case, the fact that the transition is associated with Te-Te bonding with interlayer bonds suggests that the surface may favour a different pattern than the bulk leading to a competition.…”