Magnetic structure and anisotropy of YFe_6Ga_6 and HoFe_6Ga_6

摘要

The magnetic structure of RFe_6Ga_6 intermetallic compounds with R = Y, Ho have been determined by neutron powder diffraction, ~(57)Fe Mossbauer spectroscopy, AC susceptibility, TGA (Thermo-Gravimetric Analysis) and magnetization measurements. Both compounds crystallize in the tetragonal ThMn_(12) structure (space group 14/mmm) with the magnetic structure of YFe_6Ga_6 consisting of a simple ferromagnetic alignment of Fe moments in the basal plane with a Curie temperature of 475(5) K. Gallium atoms are found to fully occupy the 8i site, with Fe and Ga atoms equally distributed over the 8j site, whilst Fe atoms fully occupy the 8f site. The average Fe moments are 1.68(10) μ_B and 1.46(10) μ_B at 15 and 293 K, respectively. The average room temperature Fe magnetic moments determined by neutron diffraction are inoverall agreement with the average Fe moment deduced from Mossbauer spectroscopy and bulk magnetization measurements on this compound. The magnetic anisotropy of the compound HoFe_6Ga_6 is also planar in the temperature range 6-290 K, with Ho magnetic moments of 9.28(20) μ_B and 2.50(20) μ_B at 6 K and 290 K, respectively, coupled anti-ferromagnetically to the Fe sublattice and a Curie temperature of 460(10) K. The magneto-crystalline anisotropies of both compounds are comparable at low temperatures.