¹⁶¹Dy Mössbauer spectroscopic study on magnetic properties of pseudo-ternary DyMn₂(Si_1-xGe_x)₂ (0 < x < 1) compounds

¹⁶¹Dy Mössbauer effect in DyMn₂(Si_1-xGe_x)₂ (0 < x < 1) has been measured at temperatures between 4.2 and 45 K. All the compounds which have antiferromagnetic ordering of Mn moments with T_N = 430-523 K transform it furthermore into other magnetic structures accompanied by ordering of Dy moments at low temperatures of 25-37 K. Magnitude of the magnetic hyperfine field and its temperature dependence have clarified that the magnetic structure of low-temperature phase is canted-ferrimagnetic in the compounds with 0.1 ≤ x ≤ 0.9, where the Mn moments tilt about 60° from the c-axis. The compounds with x = 0.8 and 0.9 have an intermediate-temperature phase between 26 and 37 K. In this phase, the Dy ions have two kinds of magnetic state, which are observed as a static Mössbauer subspectrum and a relaxation one, respectively. It is concluded that the magnetic structure of the intermediate-temperature phase is a collinear ferrimagnetic one with a long periodic arrangement. This structure can be described as a stacking of Mn moment layers along the c-axis with a + + - + + - sequence.