Angle-resolved photoemission spectroscopy of electronic structure of 1<i>T</i>-NbSeTe

Abstract

Transition metal dichalcogenides (TMDs) have attracted a lot of interest in condensed matter physics research due to the existence of multiple novel physical phenomena, including superconductivity and charge density wave order, and also TMDs provide a unique window for studying the interactions between different ground states. In this work, the electronic structure of 1<i>T</i>-NbSeTe is systematically examined by angle-resolved photoemission spectroscopy (ARPES) for the first time. A van Hove singularity (VHS) is identified at the <i>M</i> point, with binding energy of 250 meV below the Fermi level. Careful analysis is carried out to examine the band dispersions along different high symmetry directions and the possible many-body effect. However, the dispersion kink—a characteristic feature of electron-boson coupling is not obvious in this system. In TMD materials, the van Hove singularity near the Fermi level and the electron-boson (phonon) coupling are suggested to play an important role in forming charge density wave (CDW) and superconductivity, respectively. In this sense, our experimental results may provide a direct explanation for the weakened CDW and relatively low superconducting transition temperature in 1<i>T</i>-NbSeTe. These results may also provide an insight into the charge-density-wave orders in the relevant material systems.