VP15-05 Magnetic structure of rare earth intermetallic compound Er6MnTe2: neutron diffraction and magnetization study
Creators: R. Nirmala
Ganesh Jangam
A. Thamizhavel
A. V. Knotko
V. O. Yapaskurt
and  A. V. Morozkin
Publisher: name: IEEE
Year: 2025

Ternary rare earth intermetallic compounds R6TX2 where R = Rare earth, T = transition metal and X = Sb, Te and Bi, have hexagonal Fe2P-type structure (space group P-62m, no. 189, hP9) with tunable magnetic properties [1, 2]. From crystal structural point of view, the rare earth sublattice of the R6TX2 can be considered as distorted Mg-type rare-earth lattice because of the insertion of transition metal elements and p-elements and this leads to corresponding change in magnetic ordering as compared to the magnetic properties of the individual rare earth elements. The compound Er6MnTe2 is particularly interesting in the family of R6TX2 because magnetic ordering temperatures of Mn-containing samples are higher than the counterparts with T = Fe, Co, Ni and Ru. For instance, Er6FeBi2 has a ferromagnetic Curie temperature (TC) of 15 K, whereas Er6MnBi2 exhibits a higher TC of 115 K, while in the elemental Mg-type Er, the antiferromagnetic ordering temperature TN is 85 K and TC is 20 K. This has stimulated us to study the magnetic properties of Er6MnTe2 by dc magnetization and neutron diffraction experiments. From the temperature dependent magnetization, it is found that Er6MnTe2 compound orders ferromagnetically at 76 K and shows a low temperature peak at 10 K (Tm) [Fig. 1]. Saturation magnetization value at 2 K is about 6.7 µB/Er3+. From powder neutron diffraction study carried out in zero applied magnetic field, it is found that Er6MnTe2 is paramagnet from 300 K to 76 K [Fig. 2a]. From 68 K to 48 K, a set of commensurate magnetic reflections appear indicating a-axis collinear ferromagnetic ordering of Er sublattice with propagation vector (K0 = [0, 0, 0] [Fig. 2a]. Meanwhile from 38 K to 8 K, variation of intensity of magnetic reflections suggests non-collinear ab-plane ferromagnetic ordering of Er6MnTe2 [Fig. 2b]. At TC, the moments at two Er sites (3f and 3g) are different whereas at 8 K (i.e. below Tm), these reach the theoretical Er moment of 9 µB.References: 1. A. Herrero, I. R. Aseguinolaza, A. Oleaga, A. J. Garcia-Adeva, E. Apiñaniz, A. V. Garshev, V. O. Yapaskurt and A. V. Morozkin, Dalton Trans. 52 (2023) 5780 and references therein. 2. Meng Zhao, Jinlei Yao, A. Oleaga, A.V. Knotko, V.O. Yapaskurt and A.V. Morozkin, J. Solid State Chem. 323 (2023) 124058
Ternary rare earth intermetallic compounds R6TX2 where R = Rare earth, T = transition metal and X = Sb, Te and Bi, have hexagonal Fe2P-type structure (space group P-62m, no. 189, hP9) with tunable magnetic properties [1, 2]. From crystal structural point of view, the rare earth sublattice of the R6TX2 can be considered as distorted Mg-type rare-earth lattice because of the insertion of transition metal elements and p-elements and this leads to corresponding change in magnetic ordering as compared to the magnetic properties of the individual rare earth elements. The compound Er6MnTe2 is particularly interesting in the family of R6TX2 because magnetic ordering temperatures of Mn-containing samples are higher than the counterparts with T = Fe, Co, Ni and Ru. For instance, Er6FeBi2 has a ferromagnetic Curie temperature (TC) of 15 K, whereas Er6MnBi2 exhibits a higher TC of 115 K, while in the elemental Mg-type Er, the antiferromagnetic ordering temperature TN is 85 K and TC is 20 K. This has stimulated us to study the magnetic properties of Er6MnTe2 by dc magnetization and neutron diffraction experiments. From the temperature dependent magnetization, it is found that Er6MnTe2 compound orders ferromagnetically at 76 K and shows a low temperature peak at 10 K (Tm) [Fig. 1]. Saturation magnetization value at 2 K is about 6.7 µB/Er3+. From powder neutron diffraction study carried out in zero applied magnetic field, it is found that Er6MnTe2 is paramagnet from 300 K to 76 K [Fig. 2a]. From 68 K to 48 K, a set of commensurate magnetic reflections appear indicating a-axis collinear ferromagnetic ordering of Er sublattice with propagation vector (K0 = [0, 0, 0] [Fig. 2a]. Meanwhile from 38 K to 8 K, variation of intensity of magnetic reflections suggests non-collinear ab-plane ferromagnetic ordering of Er6MnTe2 [Fig. 2b]. At TC, the moments at two Er sites (3f and 3g) are different whereas at 8 K (i.e. below Tm), these reach the theoretical Er moment of 9 µB.References: 1. A. Herrero, I. R. Aseguinolaza, A. Oleaga, A. J. Garcia-Adeva, E. Apiñaniz, A. V. Garshev, V. O. Yapaskurt and A. V. Morozkin, Dalton Trans. 52 (2023) 5780 and references therein. 2. Meng Zhao, Jinlei Yao, A. Oleaga, A.V. Knotko, V.O. Yapaskurt and A.V. Morozkin, J. Solid State Chem. 323 (2023) 124058