MAGNETIC-STRUCTURES OF ER6MN23 AND DY6MN23

The R(6)Mn(23) (R = rare earth) compounds crystallize in the cubic Th6 Mn23-type structure with space group Fm ($) over bar 3m. Powder neutro n-diffraction experiments were performed on Dy6Mn23 and Er6Mn23. The m agnetic unit cell coincides with the chemical one. The R moments have a ferromagnetic non-collinear arrangement, whereas the Mn moments are parallel to the [111] direction. The magnetic structures belong to the three-dimensional Gamma(5g) irreducible representation of Fm ($) over bar 3m associated with the wave vector K = [000]. The spin configurat ions in both compounds result from the competition between the R-R, R- Mn magnetic interactions and the crystal electric field on the R ions.