Surface Charge Induced Dirac Band Splitting in a Charge Density Wave Material (TaSe4)2I

Abstract

(TaSe4)2I, a quasi-one-dimensional (1D) crystal, shows a characteristic temperature-driven metal-insulator phase transition. Above the charge density wave (CDW) temperature Tc, (TaSe4)2I has been predicted to harbor a Weyl semimetal phase. Below Tc, it becomes an axion insulator. Here, we performed angle-resolved photoemission spectroscopy (ARPES) measurements on the (110) surface of (TaSe4)2I and observed two sets of Dirac-like energy bands in the first Brillion zone, which agree well with our first-principles calculations. Moreover, we found that each Dirac band exhibits an energy splitting of hundreds of meV under certain circumstances. In combination with core level measurements, our theoretical analysis showed that this Dirac band splitting is a result of surface charge polarization due to the loss of surface iodine atoms. Our findings here shed new light on the interplay between band topology and CDW order in Peierls compounds and will motivate more studies on topological properties of strongly correlated quasi-1D materials.

arXiv comment18 pages, 4 figures. Comments are welcome

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Cited by in corpus (8)

• All Topological Bands of All Nonmagnetic Stoichiometric Materials
• Chirality locking charge density waves in a chiral crystal
• Absence of in-gap modes in charge density wave edge dislocations of the Weyl semimetal (TaSe${}_4$)${}_2$I
• Discovery of a Topological Charge Density Wave
• Memristive switching in the surface of a charge-density-wave topological semimetal
• Disorder and diffuse scattering in single-chirality (TaSe${}_4$)${}_2$I crystals
• Emergent Edge Modes in Shifted Quasi-One-Dimensional Charge Density Waves
• Ultrafast dynamics in (TaSe${}_4$)${}_2$I triggered by valence and core-level excitation