Electronic band calculation of BaPd2Sb2: Which polymorph is stable?

Iron-pnictide superconductor (Ba,K)Fe2As2 and nickelate superconductor BaNi2As2 both have the ThCr2Si2-type crystal structure. On the other hand, platinum superconductor SrPt2As2 has the CaBe2Ge2-type crystal structure. We focused on BaPd2Sb2, which contains Pd located between Ni and Pt on the periodic table. We have calculated the electronic structure of BaPd2Sb2 from first-principles, and found that the CaBe2Ge2-type structure is more stable. The Fermi surfaces of BaPd2Sb2 are two-dimensional for the CaBe2Ge2-type structure, and are three-dimensional for the ThCr2Si2-type structure. The calculated D(EF) is 32.1 States/Ry, which is comparable with that in SrPt2As2. These results strongly suggest that superconductivity also occurs in BaPd2Sb2.

•Crystal structure of BaPd2Sb2 is CaBe2Ge2-type.•Fermi surfaces are quasi-2D similar to iron pnictides.•In ThCr2Si2-type structure, Fermi surfaces are 3D.•Magnetic interaction via Pd is to be small.•Superconductivity in BaPd2Sb2 is expected.