Structure and magnetism in synthetic pyrrhotite Fe7S 8: A powder neutron-diffraction study

Anthony V. Powell, Paz Vaqueiro, Kevin S. Knight, Laurent C. Chapon, Rodolfo D. Sánchez

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Abstract

The relationship between structural and magnetic properties in stoichiometric pyrrhotite Fe7S8 has been investigated using variable-temperature neutron-diffraction data. Below its magnetic ordering temperature, TN=598(5) K, Fe7S8 exhibits a monoclinic 4C structure, related to that of NiAs, in which fully occupied cation layers alternate with cation-deficient layers. The magnetic structure consists of ferromagnetically aligned layers, with antiferromagnetic coupling of adjacent layers. The ordered moment of 3.16(1)µB at 11 K is directed at an angle of 29° to the layers. The magnetic transition is accompanied by a structural transformation from the monoclinic 4C structure to a hexagonal cation-deficient NiAs structure, in which the vacancies are statistically distributed between all layers. Although the 4C structure is recovered on cooling through the magnetic transition, the resultant phase exhibits a significant degree of intralayer cation disorder.

Original languageEnglish
Article number014415
Pages (from-to)014415-1-014415-12
JournalPhysical Review B: Condensed Matter and Materials Physics
Volume70
Issue number1
DOIs
Publication statusPublished - Jul 2004

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    Powell, A. V., Vaqueiro, P., Knight, K. S., Chapon, L. C., & Sánchez, R. D. (2004). Structure and magnetism in synthetic pyrrhotite Fe7S 8: A powder neutron-diffraction study. Physical Review B: Condensed Matter and Materials Physics, 70(1), 014415-1-014415-12. [014415]. https://doi.org/10.1103/PhysRevB.70.014415