Structure and magnetic properties of Tb(Mn1-xCox)6Sn6 compounds

Tb(Mn1-xCox)6Sn6 compounds with x = 0, 0.05, 0.10, 0.15, 0.20 and 0.25 have been studied in this paper. All of the compounds crystallize in the HfFe6Ge6-type structure (space group P6/mmm). The substitution of Co for Mn in TbMn6Sn6 results in a monotonic decrease in the lattice constants and the unit-cell volume. The ordering temperature decreases monotonically from 423 K at x=0 to 267 K at x=0.25. The reorientation of the easy-axis magnetization of TbMn6Sn6 disappeared on Co substitution at x=0.10, while for Co content x exceeding 0.15 a compensation temperature was observed in the thermal magnetization curve. The reorientation temperature decreases with Co content increase, while the compensation temperature increases. The magnetization curves up to 70 kOe at 4.5 K are given and the saturation magnetization decreases from 3.4 μB/f.u. at x=0 to 0.2 μB/f.u. at x=0.1 and then increases to 2.8 μB/f.u. at x=0.25. (author)