Fig. 2: Stripe charge ordering formation in IrTe₂ nanoflakes.

a, b Raman spectra (a) and corresponding temperature dependent Raman frequency (b) of a 65-nm-thick IrTe₂ nanoflake at various temperatures during cool-down and warm-up procedures. At T < T_s, the Raman modes, E_g at 126 cm⁻¹ and A_1g at 165 cm⁻¹, split into multiple peaks as the flake forms the stripe charge order in a. The temperature ranges for the normal (red), the stripe (blue), and intermediate coexistence (yellow) phases, are identified in b, during cooling (upper panel) and warming (lower panel). Transition temperatures T_s,dn and T_s,up are indicated by the arrows, respectively. c Spatial profile of Raman intensity map for 129 cm⁻¹ for a 43-nm-thick IrTe₂ nanoflake at T ~ 70 K. Inset: optical microscope image of the flake. d Large-scale scanning tunnelling microscopy (STM) image of a 20-nm-thick IrTe₂ flake at T = 85 K (scale bar, 300 nm). The flake has only stripe-phase charge-ordered domains, illustrated by red, green, and blue lines. Black lines indicate domain boundaries between three equivalent stripe-phase charge-ordered domains. e Atomically resolved STM image of d at T = 85 K representing a uniform striped area with 5 × 1 surface reconstruction (scale bar, 2 nm). f Zoomed-in STM image of two charge-ordered phases indicated by red square in d showing that the two phases coexist at the boundary (scale bar, 20 nm). g Scanning tunnelling spectroscopy (STS) spectra at T = 85 K taken on IrTe₂ nanoflakes with d = 47, 80, and 148 nm, as indicated in the plot.