Magnetic ordering in Er2Fe2Si2C and Tm2Fe2Si2C
Australian Institute of Physics
The magnetic ordering of two members of the R2Fe2Si2C (R = rare-earth) series of compounds (monoclinic Dy2Fe2Si2C-type structure with the C2/m space group), Er2Fe2Si2C and Tm2Fe2Si2C, have been studied by neutron powder diffraction and 166Er Mössbauer spectroscopy, complemented by magnetisation and specific heat measurements. In both cases, antiferromagnetic ordering of the R sublattice is observed, with Neel temperatures of 4.8(2) K and 2.6(3) K for Er2Fe2Si2C and Tm2Fe2Si2C, respectively. The magnetic structures of the Erand Tm-based compounds are quite different from those found for the other members of the R2Fe2Si2C series. Previous studies show that the common magnetic structure of the heavy- R2Fe2Si2C compounds involves ordering of the R sublattice along the b-axis with a propagation vector k = [0, 0, ½]. However, the antiferromagnetic structure of the Er sublattice in Er2Fe2Si2C is described by k = [½, ½, 0] with the Er magnetic moments lying close to the ac-plane. Tm2Fe2Si2C is found to exhibit a more complex magnetic structure that is characterised by a square-wave modulation of the Tm magnetic moments along the a-axis and a cell-doubling along the b-axis with k = [0.403(1), ½, 0]. The differences in the magnetic structures of these compounds are interpreted in terms of the RKKY exchange interaction, which depends on the R-R interatomic distances, and crystal field effects acting on the R3+ ions.
Antiferromagnetism, Thulium compounds, Crystal field, Erbium compounds, Exchange interactions, Magnetic moments, Magnetic properties, Moessbauer effect, Neel temperature, Neutron diffraction, Rare earths
Susilo, R. A., Cadogan, J. M., Hutchison, W. D., Campbell, S. J., Avdeev, M., Ryan, D. H., & Namiki, T. (2015). Magnetic ordering in Er2Fe2Si2C and Tm2Fe2Si2C. Paper presented at 39th Annual Condensed Matter and Materials Meeting, Charles Sturt University, Wagga Wagga, NSW, 3 – 6 February 2015. Retrieved from: https://physics.org.au/wp-content/uploads/cmm/2015/Wagga2015_10_Handbook.pdf