Examining the surface phase diagram of IrTe2 with photoemission

Abstract

In the transition metal dichalcogenide IrTe 2 , low-temperature charge-ordered phase transitions involving Ir dimers lead to the occurrence of stripe phases of different periodicities, and nearly degenerate energies. Bulksensitive measurements have shown that, upon cooling, IrTe 2 undergoes two such first-order transitions to (5 × 1 × 5) and (8 × 1 × 8) reconstructed phases at T c 1 ∼ 280 K and T c 2 ∼ 180 K, respectively. Here, using surface sensitive probes of the electronic structure of IrTe 2 , we reveal the first-order phase transition at T c 3 = 165 K to the (6 × 1) stripes phase, previously proposed to be the surface ground state. This is achieved by combining x-ray photoemission spectroscopy and angle-resolved photoemission spectroscopy, which give access to the evolution of stripe domains and a particular surface state, the energy of which is dependent on the Ir dimer length. By performing measurements over a full thermal cycle, we also report the complete hysteresis of all these phases.

Uniaxial strain-induced phase transition in the 2D topological semimetal IrTe2

“…The corresponding Fermi surface (Fig. 1h) shows three-fold rotational symmetry consistent with the literature [26][27][28][29] . Upon cooling the unstrained sample ( Fig.…”

“…4). The ratio of the peak areas tracks the relative dimer density and indicates a mixture of phases in unstrained samples 26,29 . In contrast, for strained samples an increase of the Ir 3+δ+ peak produces a ratio that accords perfectly with the expectation for a single 6 × 1 phase (0.67).…”

Superconductivity emerging from a stripe charge order in IrTe2 nanoflakes

“…Our findings unequivocally emphasise that the superconductivity in IrTe 2 nanoflakes, which emerges from the preexisting stripe order, is highly distinct from that in doped bulk IrTe 2 . On pristine IrTe 2 bulk or surface, the 5a 0 stripe phase undergoes multiple transitions to other nearly-degenerate stripe phases that have different periods such as 8a 0 and 6a 0 , and also a honeycomb phase 35,[43][44][45] . The complex stripe ordering formation is a result of subtle balance between local interactions of Ir-Ir dimerization and Te-Te depolymerisation.…”

Break of symmetry at the surface of IrTe$_2$ upon phase transition measured by X-ray photoelectron diffraction

“…IrTe 2 undergoes several structural first-order phase transitions below RT. The system goes from a trigonal unit cell of CdI 2 -type (P 3m1) to a monoclinic unit cell (P 1) accompanied by a sudden jump in resistivity and magnetic susceptibility at T c 1 = 278 K [6,7,8,9,10,11,12,13,14]. In this first charge ordered phase, one-dimensional stripes of Ir dimers [15,16] appear due to a large decrease of their bond length and lead to a bulk (5 × 1 × 5) superstructure [16,17,6,18,10,19,20], see Figure 1 (c-d).…”