The Electronic Structure of the Nickel Pnictide Superconductor BaNi$_{2}$As$_{2}$

The electronic structure of the nickel pnictide superconductor BaNi$_{2}$As$_{2}$ is investigated with angle-resolved photoemission spectroscopy. While the iron pnictide superconductors display unconventional superconducting properties, superconductivity in the non-magnetic nickel compounds is believed to be more conventional. Here we present the electronic structure of BaNi$_{2}$As$_{2}$ and compare it to the iron pnictide superconductors. While differences in the electronic structures exist, similarities raise questions about the nature of the nickel pnictide superconductivity. Low energy electron diffraction also reveals distinct differences in the surface structure of nickel and iron compounds. Temperature dependence across the T$_{c}$ = 140K structural phase transition is also investigated.