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

Neutron diffraction study has been performed on the Tb5Sb3 and Tb5Si1.5Sb1.5 compounds (hexagonal Mn5Si3-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 Tb5Sb3 presents five subsequent changes in magnetic structure at similar to 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 Tb5Si1.5Sb1.5 shows two subsequent changes in magnetic structure at 123 and 66 K: paramagnet -> sine modulated antiferromagnet I -> sine modulated antiferromagnet II. The Tb5Si3, Tb5Sb3 and Tb5Si1.5Sb1.5 have the different magnetic structure in the full temperature range. (C) 2011 Elsevier B.V. All rights reserved.