# First-principles calculations of the magnetic and electronic structures of MnP under pressure

## TL;DR

This study uses first-principles calculations to explore how pressure influences the magnetic and electronic structures of MnP, revealing complex magnetic phases and charge carrier behaviors linked to its crystal structure.

## Contribution

It provides detailed first-principles insights into pressure-dependent magnetic states and electronic properties of MnP, including spiral and ferromagnetic phases, and their relation to superconductivity.

## Key findings

- Magnetic ground states change from c-axis to b-axis with pressure.
- Spiral propagation vector varies nonmonotonically with pressure.
- Electronic structures show quasi-one-dimensional and three-dimensional charge carriers.

## Abstract

Manganese monophosphide (MnP) shows complicated magnetic states varying with both temperature and pressure. We calculate the magnetic and electronic structures of MnP at different pressures using first-principles methods and obtain spiral ground states whose propagation vector changes from the c-axis at low pressure to the b-axis at high pressure. In between, we find a ferromagnetic state, as observed in the experimental phase diagram. The propagation vector of the spiral states is found to vary nonmonotonically with pressure, consistent with neutron measurements. Our results indicate that the complicated magnetic phase diagram originates from a delicate competition between neighboring exchange interactions between the Mn-ions. At all pressures, the electronic structures indicate the existence of quasi-one-dimensional charge carriers, which appear in the ferromagnetic state and become gapped in the spiral state, and anisotropic three-dimensional charge carriers. We argue that this two-fluid behavior originates from the special crystal structure of MnP and may be relevant for understanding the pairing mechanism of the superconductivity at the border of the high pressure spiral phase.