Magnetic properties of Th3P4-type Tb4Sb3-X{Si, Ge, Bi}(X) solid solutions

A. V. Morozkin (1) , D. Buddhikot (2) , A.K. Nigam , Olivier Isnard (3) , Y. Mozharivskyj (4)

1 MSU - Lomonosov Moscow State University
2 School of Technology and Computer Science [TIFR]
3 NEEL - MRS - Matériaux, Rayonnements, Structure
4 Department of Chemical Engineering [Hamilton, Ontario]

The magnetic properties of Tb4Sb2Bi, Tb4Sb2.75Ge0.25 and Tb4Sb2.3Si0.7 solid solutions (Th3P4-type, cubic; cI28, space group I (1) over bar 3d, No. 220) have been investigated by means of magnetization and neutron diffraction studies. The magnetization measurements indicate that the Tb4Sb2Bi compound orders magnetically at 120 K (T-N) and 50 K (T-C). The magnetization vs. field isotherm at 5 K shows signature of ferromagnetic order. Neutron diffraction experiment in zero applied magnetic field shows that below T-N = 125(4) K Tb4Sb2Bi exhibits a antiferromagnetic flat spiral type ordering with wave vector K-1 = [+/- K-X, +/- K-X, +/- K-X] (K-X value changes from 0.1033 up to 0.158 in the temperature interval down to 2 K). Below T-m = 70(4) K the decreasing of antiferromagnetic component coincides with increasing of the ferromagnetic component and about T-CN = 55(4) K, Tb4Sb2Bi shows ferromagnetic transition. At 2 K, the magnetic structure of Tb4Sb2Bi is ferromagnetic cone and the cone axis is along [1 1 1] direction. Neutron diffraction study of Tb4Sb2.75Ge0.25 indicate an antiferromagnetic ordering at 155(4) K (ferromagnetic cone with K-1 = [+/- 0.136(2), +/- 0.136(2), +/- 0.136(2)]) and ferromagnetic ordering (sharp increasing of ferrornagnetic component) at 145(4) K. The K-X value is nearly constant from 155 K down to 2 K. At 2 K, the magnetic structure of Tb4Sb2.75Ge0.25 is ferromagnetic cone with a weak antiferromagnetic component and the cone axis is along [1 1 1] direction. Low field magnetisation measurements on Tb4Sb2.3Si0.7 indicate a ferromagnetic ordering at T-C similar to 180 K. Thus small substitutions of Bi, Ge and Si at Sb-site of Tb4Sb3 are found to increase the magnetic ordering temperature of the parent compound.

Domaines: Science des matériaux [cond-mat.mtrl-sci]

A. V. Morozkin, D. Buddhikot, A.K. Nigam, Olivier Isnard, Y. Mozharivskyj. Magnetic properties of Th3P4-type Tb4Sb3-X{Si, Ge, Bi}(X) solid solutions. Journal of Alloys and Compounds, 2009, 478, pp.22-29. ⟨10.1016/j.jallcom.2008.10.168⟩. ⟨hal-00988694⟩