Spectral signatures of a unique charge density wave in Ta${}_2$NiSe${}_7$

Abstract

Charge Density Waves (CDW) are commonly associated with the presence of near-Fermi level states which are separated from others, or "nested", by a wavector of $\mathbf{q}$. Here we use Angle-Resolved Photo Emission Spectroscopy (ARPES) on the CDW material Ta${}_2$NiSe${}_7$ and identify a total absence of any plausible nesting of states at the primary CDW wavevector $\mathbf{q}$. Nevertheless we observe spectral intensity on replicas of the hole-like valence bands, shifted by a wavevector of $\mathbf{q}$, which appears with the CDW transition. In contrast, we find that there is a possible nesting at $2q$, and associate the characters of these bands with the reported atomic modulations at $2q$. Our comprehensive electronic structure perspective shows that the CDW-like transition of Ta${}_2$NiSe${}_7$ is unique, with the primary wavevector $\mathbf{q}$ being unrelated to any low-energy states, but suggests that the reported modulation at $2q$, which would plausibly connect low-energy states, might be more important for the overall energetics of the problem.

References in corpus (12)

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• Band dependence of charge density wave in quasi-one-dimensional Ta2NiSe7 probed by orbital magnetoresistance
• The spontaneous symmetry breaking in Ta${}_2$NiSe${}_5$ is structural in nature
• Detecting photoelectrons from spontaneously formed excitons

Cited by in corpus (2)

• Sliding phasons in Moiré Ladders
• Disorder-mediated linear and nonlinear magnetotransport in the charge-density-wave material $\mathrm{T}{\mathrm{a}}_2\mathrm{NiS}{\mathrm{e}}_7$