The relation between local structural distortion and the low-temperature magnetic anomaly in Fe7S8

D. Koulialias*, E. Canévet, M. Charilaou, P. G. Weidler, J. F. Löffler, A. U. Gehring

*Corresponding author for this work

Research output: Contribution to journalJournal articleResearchpeer-review

Abstract

Structural defects on an atomic level can crucially impact the magnetic properties of a material. We study this phenomenon by means of magnetometry and powder neutron diffraction on a stoichiometric, monoclinic pyrrhotite (Fe7S8), which is a classic omission structure with a magnetic anomaly at about 30 K. The initial structural distortion of the pyrrhotite at 300 K caused by the vacancy arrangement decreases upon cooling, and simultaneous to the magnetic anomaly the anisotropic contraction of the unit cell homogenizes the covalency of the Fe-Fe bonds with lengths less than 3.0 Å and the Fe-S-Fe bond angles. These changes on the atomic level affect the spin-orbit coupling and the super-exchange interactions in Fe7S8, and trigger the low-temperature magnetic anomaly within a crystallographically stable system.

Original languageEnglish
Article number425803
JournalJournal of Physics Condensed Matter
Volume30
Issue number42
Number of pages8
ISSN0953-8984
DOIs
Publication statusPublished - 2018

Keywords

  • Exchange interactions
  • Magnetic anisotropy
  • Monoclinic pyrrhotite
  • Spin orbit coupling
  • Vacancies

Cite this

Koulialias, D., Canévet, E., Charilaou, M., Weidler, P. G., Löffler, J. F., & Gehring, A. U. (2018). The relation between local structural distortion and the low-temperature magnetic anomaly in Fe7S8. Journal of Physics Condensed Matter, 30(42), [425803]. https://doi.org/10.1088/1361-648X/aadf54