Two-layer compounds in rare earth-{Fe, Co, Ni, Rh, Pd, Pt}-Te systems: crystal structure and magnetic properties

Abstract The partial isothermal sections of {Gd, Ho}-Ni-Te and Gd-Co-Te systems (~40–100 at. % of rare earth) have been investigated at 1070 K by X-ray and electron microprobe analysis. The Y5Ni2Te2-type {Tb, Dy, Ho}5Fe2Te2 and {Gd, Tb, Dy, Ho}5{Co, Ni}2Te2 (space group Cmcm, No. 63, oC36), Er7Ni2Te2-type Er7Co2Te2, {Y, Dy, Ho}7Ni2Te2, Ho7{Rh, Pd}2Te2 and {Y, Gd}7Pt2Te2 (space group Imm2, No. 44, oI22), Fe2P-type Ho6NiTe2 (space group P-62m, No. 189, hP9) and Sc6PdTe2-type Ho6{Rh, Pd}Te2 and {Y, Gd}6PtTe2 (space group Pnma, No. 62, oP36) compounds have been established using powder X-ray diffraction studies. Magnetization measurements show that the Y5Ni2Te2-type {Tb, Dy, Ho}5Fe2Te2, {Gd, Tb, Dy}5Co2Te2 and {Tb, Ho}5Ni2Te2 compounds exhibit a high-temperature ferromagnetic ordering with low-temperature spin-reorientation transition for Tb-, Dy- and Ho-containing compounds. Below Curie temperature, Tb5Fe2Te2, Tb5Co2Te2 and Ho5Ni2Te2 are soft ferromagnets, while they show hard magnetic properties below spin-reorientation transition. At 2 K, Tb5Co2Te2 and Tb5Fe2Te2 exhibit a coercive field of 35 kOe and ~30 kOe and the residual magnetization of 17.2 μB and 22.9 μB per formula unit, leading to theoretical maximum energy product of ~620 kJ/m3 and ~700 kJ/m3, respectively. Ho5Ni2Te2 reaches a maximum magnetic entropy change of −10.0 J/kg⋅K and −9.4 J/kg⋅K for a magnetic field change of 0–50 kOe at 45 K and 20 K, respectively.