Electronic structures and effective models in BaPtSb and BaPtAs with ordered honeycomb structures

We investigate the low-energy electronic properties and construct the effective model Hamiltonians in the normal state for new materials BaPtSb and BaPtAs with ordered honeycomb structures.
The preliminary experimental study suggested that the former compound may be a candidate of the time-reversal symmetry breaking superconductors.
The low-energy electronic structures obtained from the first principles calculation mainly consist of Pt 5$d$ and Sb/As 5$p$/4$p$ orbitals, where there exist the strong hybridizations between both orbitals. We show that the main parts in the low-energy region including the Fermi surface are well described using renormalized 3 bands consisting of dominant Pt 2 bands and Sb/As 1 band. Our result provides a starting point for microscopic investigation in the superconducting states for the materials with the hexagonal structure.