Magnetic properties of Fe2P-type R6CoTe2 compounds (R=Gd–Er)

The magnetic structure of the Fe2P-type R6CoTe2 phases (R=Gd–Er, space group P6¯2m) has been investigated through magnetization measurement and neutron powder diffraction. All phases demonstrate high-temperature ferromagnetic and low-temperature transitions: TC=220 K and TCN=180 K for Gd6CoTe2, TC=174 K and TCN=52 K for Tb6CoTe2, TC=125 K and TCN=26 K for Dy6CoTe2, TCN=60 K and TN=22 K for Ho6CoTe2 and TCN∼30 K and TN∼14 K for Er6CoTe2.Between 174 and 52 K Tb6CoTe2 has a collinear magnetic structure with K0=[0, 0, 0] and with magnetic moments along the c-axis, whereas below 52 K it adopts a non-collinear ferromagnetic one.Below 60 K the magnetic structure of Ho6CoTe2 is that of a non-collinear ferromagnet. The holmium magnetic components with a K0=[0, 0, 0] wave vector are aligned ferromagneticaly along the c-axis, whereas the magnetic component with a K1=[1/2, 1/2, 0] wave vector are arranged in the ab plane. The low-temperature magnetic transition at ∼22 K coincides with the reorientation of the Ho magnetic component with the K0 vector from the collinear to the non-collinear state.Below 30 K Er6CoTe2 shows an amplitude-modulate magnetic structure with a collinear arrangement of magnetic components with K0=[0, 0, 0] and K1=[1/2, 1/2, 0]. The low-temperature magnetic transition at ∼14 K corresponds to the variation in the magnitudes of the MErK0 and MErK1 magnetic components.In these phases, no local moment was detected on the cobalt site.The magnetic entropy of Gd6CoTe2 increases from ΔSmag=−4.5 J/kg K at 220 K up to ΔSmag=−6.5 J/kg K at 180 K for the field change Δμ0H=0–5 T.

The novel Fe2P-type R6CoTe2 phases (R=Gd–Er, space group P6¯2m) show ferromagnetic type ordering in the temperature range 14–220 K.All compounds demonstrate high-temperature ferromagnetic and low-temperature antiferromagnetic ordering.The magnetic entropy of Gd6CoTe2 increases from ΔSmag=−4.5 J/kg K at 220 K up to ΔSmag=−6.5 J/kg K at 180 K for the field change Δμ0H=0–5 T.The R6CoTe2 compounds exhibit the commensurate magnetic structures with wave vectors K0=[0, 0, 0] and K1=[1/2, 1/2, 1/2].Figure optionsDownload as PowerPoint slide