Commensurate versus incommensurate charge ordering near the superconducting dome in Ir1−xPtxTe2 revealed by resonant x-ray scattering

The electronic-structural modulations of ${\mathrm{Ir}}_{1\ensuremath{-}x}{\mathrm{Pt}}_x{\mathrm{Te}}₂$ ($0\ensuremath{\leqq}x\ensuremath{\leqq}0.12$) have been examined by resonant elastic x-ray scattering (REXS) and resonant inelastic x-ray scattering (RIXS) techniques at both the Ir and Te edges. Charge-density-wave-like superstructures with wave vectors of $\mathbf{Q}=(1/5\phantom{\rule{4pt}{0ex}}0\phantom{\rule{4pt}{0ex}}\ensuremath{-}1/5)$, $(1/8\phantom{\rule{4pt}{0ex}}0\phantom{\rule{4pt}{0ex}}\ensuremath{-}1/8)$, and $(1/6\phantom{\rule{4pt}{0ex}}0\phantom{\rule{4pt}{0ex}}\ensuremath{-}1/6)$ are observed on the same sample of ${\mathrm{IrTe}}₂$ at the lowest temperature, the patterns of which are controlled by the cooling speeds. In contrast, superstructures around $\mathbf{Q}=(1/5\phantom{\rule{4pt}{0ex}}0\phantom{\rule{4pt}{0ex}}\ensuremath{-}1/5)$ are observed for doped samples ($0.02\ensuremath{\leqq}x\ensuremath{\leqq}0.05$). The superstructure reflections persist to higher Pt substitution than previously assumed, demonstrating that a charge-density wave (CDW) can coexist with superconductivity. The analysis of the energy-dependent REXS and RIXS line shape reveals the importance of the Te $5p$ state rather than the Ir $5d$ states in the formation of the spatial modulation of these systems. The phase diagram reexamined in this work suggests that the CDW incommensurability may correlate with the emergence of superconducting states such as ${\mathrm{Cu}}_x{\mathrm{TiSe}}₂$ and ${\mathrm{Li}}_x{\mathrm{TaS}}₂$.