Magnetic properties of Fe 2GeMo 3N; An experimental and computational study

Peter D. Battle, Lev A. Sviridov, Russell J. Woolley, Fernande Grandjean, Gary J. Long, C. Richard A. Catlow, Alexey A. Sokol, Aron Walsh, Scott M. Woodley

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Abstract

A polycrystalline sample of Fe 2GeMo 3N 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. Fe 2GeMo 3N adopts the cubic η-carbide structure with a = 11.1630(1) Å at 300 K. The electrical resistivity was found to be ∼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 Fe 4 tetrahedra; the ordered atomic magnetic moments, 1.90(4) μ B per Fe atom at 1.8 K, align along a <111> direction. DFT predicts an ordered moment of 1.831 μ B 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 languageEnglish
Pages (from-to)15606-15613
Number of pages8
JournalJournal of Materials Chemistry
Volume22
Issue number31
DOIs
Publication statusPublished - 2012 Aug 21

All Science Journal Classification (ASJC) codes

  • Chemistry(all)
  • Materials Chemistry

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    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 Fe 2GeMo 3N; An experimental and computational study. Journal of Materials Chemistry, 22(31), 15606-15613. https://doi.org/10.1039/c2jm32574h