### Abstract

A polycrystalline sample of Fe2GeMo3N has been synthesized by the reductive nitridation of a mixture of binary oxides in a flow of 10% dihydrogen in dinitrogen. The reaction product has been studied by magnetometry, neutron diffraction and Mössbauer spectroscopy over the temperature range 1.8 ≤ T/K ≤ 700. The electronic structure and magnetic coupling have been modelled by Density Functional Theory (DFT) and Monte Carlo methods. Fe2GeMo3N adopts the cubic η-carbide structure with a = 11.1630(1) Å at 300 K. The electrical resistivity was found to be [similar]0.9 mΩ cm over the temperature range 80 ≤ T/K ≤ 300. On cooling below 455 K the compound undergoes a transition from a paramagnetic to an antiferromagnetic state. The magnetic unit cell contains an antiferromagnetic arrangement of eight ferromagnetic Fe4 tetrahedra; the ordered atomic magnetic moments, 1.90(4) μB per Fe atom at 1.8 K, align along a <111> direction. DFT predicts an ordered moment of 1.831 μB per Fe. A random phase approximation to the DFT parameterised Heisenberg model yields a Néel temperature of 549 K, whereas the value of 431 K is obtained in the classical limit for spin. Monte Carlo calculations confirm that the experimentally determined magnetic structure is the lowest-energy antiferromagnetic structure, but with a lower Néel temperature of 412 K. These results emphasise the potential of these computational methods in the search for new magnetic materials.

Original language | English |
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Pages (from-to) | 15606-15613 |

Journal | Journal of Materials Chemistry |

Volume | 22 |

Issue number | 31 |

DOIs | |

Publication status | Published - 2012 |

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## Cite this

Battle, P. D., Sviridov, L. A., Woolley, R. J., Grandjean, F., Long, G. J., Catlow, C. R. A., Sokol, A. A., Walsh, A., & Woodley, S. M. (2012). Magnetic properties of Fe2GeMo3N; an experimental and computational study.

*Journal of Materials Chemistry*,*22*(31), 15606-15613. https://doi.org/10.1039/c2jm32574h