Structures, phase transitions, and magnetic properties of Co3Si from first-principles calculations

TL;DR

This study uses first-principles calculations to explore the crystal structures, phase transitions, and magnetic properties of Co3Si, revealing new stable phases and insights into its magnetic behavior.

Contribution

It provides a comprehensive first-principles analysis of Co3Si's structures and magnetic properties, identifying the most stable phases and their magnetic states.

Findings

Hexagonal Co3Si is non-magnetic and less stable at zero temperature.

The ferromagnetic hexagonal structure is dynamically unstable.

An orthorhombic structure is more stable and has the lowest energy.

Abstract

Co3Si was recently reported to exhibit remarkable magnetic properties in the nanoparticle form [Appl. Phys. Lett. 108, 152406 (2016)], yet better understanding of this material is to be promoted. Here we report a study on the crystal structures of Co3Si using adaptive genetic algorithm, and discuss its electronic and magnetic properties from first-principles calculations. Several competing phases of Co3Si have been revealed from our calculations. We show that the hexagonal Co3Si structure reported in experiments has lower energy in non-magnetic state than ferromagnetic state at zero temperature. The ferromagnetic state of the hexagonal structure is dynamically unstable with imaginary phonon modes and transforms to a new orthorhombic structure, which is confirmed by our structure searches to have the lowest energy for both Co3Si and Co3Ge. Magnetic properties of the experimental hexagonal structure and the lowest-energy structures obtained from our structure searches are investigated in detail.