Pressurized phase transition cascade in BaMn$_2$P$_2$ and BaMn$_2$As$_2$

TL;DR

This study uses DFT+U calculations to reveal pressure-induced phase transitions in BaMn$_2$P$_2$ and BaMn$_2$As$_2$, showing potential for superconductivity under high pressure.

Contribution

It reports the first detailed theoretical analysis of pressure-driven magnetic and structural phase transitions in these compounds, highlighting their potential as superconductors.

Findings

Transition from AFM insulator to AFM metal at 6.4 GPa (BaMn$_2$P$_2$) and 8.3 GPa (BaMn$_2$As$_2$)

Sequence of magnetostructural phase transitions under increasing pressure

Potential emergence of superconductivity above 6-8 GPa with increasing critical temperature

Abstract

The structural analogue of iron-based superconductors the BaMn$_2$P$_2$ and BaMn$_2$As$_2$ 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 BaMn$_2$P$_2$ and 8.3 GPa for BaMn$_2$As$_2$. 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.