Prediction of Antiferromagnetism in Chromium Analog (BaCr₂P₂) of Iron Pnictide Confirmed by Synthesis

We have performed density-functional theory (DFT) calculations for BaCr₂P₂. It is a chromium analog to the parent compound BaFe₂As₂ for a series of iron-pnictide superconductors. By combining evolutionary methods with DFT, we predict that BaCr₂P₂ has the same crystal structure as its iron-pnictide analog[1]. DFT also predicts Neel antiferromagnetic order over the chromium sites. A simple hopping model over a square lattice of chromium atoms that includes only the principal 3d_xz and 3d_yz orbitals suggests that such checkerboard antiferromagnetic order is due to residual nesting of the Fermi surfaces that is obscured by a Lifshitz transition[1]. The DFT prediction has been confirmed experimentally after the synthesis of polycrystalline samples of BaCr₂P₂. X-ray diffraction recovers the predicted crystal structure to high accuracy, while magnetic susceptibility and specific-heat measurements are consistent with an antiferromagnetically ordered state at temperatures below T_N ~ 60 K [1].

[1] R.A. Jishi, J.P. Rodriguez, T.J. Haugan and M.A. Susner, J. Phys.: Condens. Matter 32, 025502 (2020).