Pressurized Phase Transitions Cascade in BaMn2P2 and BaMn2As2

Abstract

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 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, 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 superconductors under pressure (above 6–8 GPa) with critical temperature growing under pressure.