The magnetic ordering in the Ho 6FeTe 2 compound

Abstract

The magnetic structure of the ternary intermetallic compound Ho 6FeTe 2 (hexagonal Zr 6CoAs 2 structure type, a ternary ordered variant of the Fe 2P-type; space group P 6 ¯ 2 m , No 189) has been investigated by neutron diffraction and magnetization measurements. The neutron diffraction study shows that in between the temperatures T N ∼ 24 K and T C ∼ 8 K the magnetic moments of the Ho atoms adopt a flat helix ordering with elliptical envelope having a wave vector K = [0, 0, ∼1/9], the helix axis being coincident with the c-axis (with maximal magnetic moments of M H o 1 = 6.5 ( 7 ) μ B and M H o 2 = 8.0 ( 7 ) μ B , at 10 K). Below the T C ∼ 8 K the magnetic structure of Ho 6FeTe 2 changes to a ferromagnetic cone: superposed on the helix ordering within the basal plane a ferromagnetic ordering with K = [0, 0, 0] and moments pointing in the c-direction appears. At 2 K the total maximal magnetic moments amount to M H o 1 = 9.1 ( 7 ) μ B and M H o 2 = 9.6 ( 7 ) μ B with a ferromagnetic component on the H o 1 site of M c H o 1 = 2.2 ( 5 ) μ B and on the H O 2 site of M c H o 2 = 5.2 ( 5 ) μ B . No local moment was detected on the iron atomic site in this compound. Magnetization measurements confirm the first magnetic transition at ∼26 K and the second at ∼10 K. The magnetization vs. field data obtained at 2.5 K show soft ferromagnetic behavior, with a saturation magnetization of 7.9 μ B/Ho 3+.