Nematicity and charge density wave in BaNi₂As₂

Unconventional superconductivity always emerges in proximity to emergent electronic orders. In the iron-based superconductors, a ubiquitous intertwined order persists that consists of a C₄-symmetry breaking structural transition and collinear spin-density wave. BaNi₂As₂, like its well-known iron-based superconductor analogue, BaFe₂As₂, also hosts a C₄-symmetry-breaking structural transition coupled to a unidirectional charge density wave (CDW), providing an exciting platform to study the interplay of nematicity and CDW. In this talk, I will present our systematic angle-resolved photoemission spectroscopy study of the BaNi₂As₂ system. In particular, we report clear spectroscopic signatures that correspond to the distinct structural and CDW transitions. In addition, I will also present a comparison of the electronic structure measurements in the presence and absence of an external uniaxial strain and discuss the implications of the existence of nematic fluctuations in this system.