Pressurized phase transition cascade in BaMn₂P₂ and BaMn₂As₂

The structural analogue of iron-based superconductors the BaMn₂P₂ and BaMn₂As₂ compounds under hydrostatic pressure upto 140 GPa were studied within the framework of DFT+U. The transition from an antiferromagnetic (AFM) insulator to an antiferromagnetic metal is observed under pressure of 6.4 GPa for BaMn₂P₂ and 8.3 GPa for BaMn₂As₂. This second order phase transition to the AFM metallic state provides an appropriate normal state for possible superconductivity in these materials. Moreover, a further increase in pressure leads to a series of first order magnetostructural phase transitions between different antiferromagnetic phases, then to a ferromagnetic metal and finally to a nonmagnetic metal. In case of doping these compounds could potentially be a superconductors under pressure (above 6-8 GPa) with critical temperature growing under pressure.