Magnetic order of Mn5Si3-type Tb5Sb3 and Tb5Si1.5Sb1.5

Abstract Neutron diffraction study has been performed on the Tb 5 Sb 3 and Tb 5 Si 1.5 Sb 1.5 compounds (hexagonal Mn 5 Si 3 -type, hP16, P6 3 /mcm) to understand their magnetic structures. The temperature dependence of neutron diffraction results proves that these intermetallics show a complex magnetic ordering. The Tb 5 Sb 3 presents five subsequent changes in magnetic structure at ∼150, 119, 85, 70 and 54 K on cooling: paramagnet→antiferromagnetic flat spiral→ferromagnetic cone→antiferromagnetically canted ferromagnetic cone→canted AF→sine modulated AF. The Tb 5 Si 1.5 Sb 1.5 shows two subsequent changes in magnetic structure at 123 and 66 K: paramagnet→sine modulated antiferromagnet I→sine modulated antiferromagnet II. The Tb 5 Si 3 , Tb 5 Sb 3 and Tb 5 Si 1.5 Sb 1.5 have the different magnetic structure in the full temperature range.