Correlation between Crystal-Structure Evolution and Valence-Band Characteristics among Multiple 1T-TaS2 Phases

Abstract 1T-TaS2 is a two-dimensional strongly correlated electron material featuring broadband saturable absorption. Although the band structures of 1T-TaS2 in distinct phases have been reported, the correlation between the evolution of electronic band structure and crystal structure across different phases remains rarely explored. In this work, the two-component exothermic signature in heating differential scanning calorimetry (DSC) measurements points to sequential overlapping charge-density-wave (CDW) rearrangements for the commensurate phase (Cp) to intermediate phase (Ip) to triclinic phase (Tp) evolution, rather than a single sharp transition. Additionally, temperature-dependent synchrotron-based angle-resolved photoemission spectroscopy (ARPES), combined with variable-temperature X-ray diffraction (XRD), Raman spectroscopy, and density-functional-theory (DFT) calculations, is employed to unravel the interplay between valence-band electronic structures and crystal structures of 1T-TaS2 in its commensurate, intermediate, and triclinic phases. This work provides valuable references for the practical utilization of 1T-TaS2 under varied thermal conditions.