Neutron diffraction and 119 Sn M¨ ossbauer study of

The magnetic properties of Sm3Ag4Sn4 have been investigated using bulk magnetization, 119 Sn Mossbauer spectroscopy and neutron diffraction. We find that the Neel temperature (TN) is 26.0(5) K, well above the value of ∼ 9K previously determined using magnetic susceptibility measurements. Neutron diffraction data indicate that the Sm moments most likely adopt either the IP mmm or IP mmmmagnetic space groups, neither of which allows order at the 2d site, in marked contrast to the vast majority of other compounds in the R3T4X4 family. Transferred hyperfine field models suggest that the IP mmmis the only group that is consistent with the 119 Sn Mossbauer results. We derive a samarium moment of 0.47 ± 0.10 μB on the Sm 4e site at 3 K. 119 Sn Mossbauer spectroscopy shows that the system undergoes a spin reorientation transition at 8.3(3) K, where the moments rotate towards the a-axis. (Some figures in this article are in colour only in the electronic version)