Domain Dependent Fermi Arcs Observed in a Striped Phase Dichalcogenide

Solids undergoing symmetry breaking phase transitions commonly exhibit domains of low symmetry phases with various sizes and morphological shapes. Usually, the shapes of these domains are not directly related to the nature of symmetry breaking. Here, an interesting example of a layered dichalcogenide with a triangular lattice is shown, in which symmetry breaking of electronic charge/orbital is accompanied by formation of striped domains and exotic surface states with peculiar spin textures. Using angle-resolved photoemission spectromicroscopy, the mesoscopic striped domains in the layered IrTe₂ are observed across the first order phase transition at ≈280 K. Under further cooling down to 47 K, the striped domains evolve into trijunction domains with electronic anisotropy in three directions. Each domain harbors quasi 1D surface bands forming fragmented Fermi surfaces (Fermi arcs) with peculiar spin polarization revealed by spin-resolved photoemission spectroscopy. The Fermi arc corresponds to an edge state of the 2D bulk electronic bands truncated at the surface, indicating an interesting interplay between the symmetry breaking, surface electronic structure, and the spin state.