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.
@article{arxiv.1704.04514,
title = {Structures, phase transitions, and magnetic properties of Co3Si from first-principles calculations},
author = {Xin Zhao and Shu Yu and Shunqing Wu and Manh Cuong Nguyen and Cai-Zhuang Wang and Kai-Ming Ho},
journal= {arXiv preprint arXiv:1704.04514},
year = {2017}
}