The nature of magnetic ordering in TbNi2B2C

The nature of the magnetic ordering in TbNi2B2C has been investigated using neutron diffraction techniques on powdered polycrystalline samples. The results show that the Tb moments order below 15.5 K into an incommensurate magnetic structure. The magnetic order consists of a longitudinal modulation of the Tb moments with a wave vector of (0.556 0 0) at 1.5 K along the a*-direction. On increasing the temperature from 1.5 K, the modulation wave vector decreases, goes through a minimum at approximate to 5 K, and then increases up to T-N. The experimental data also indicate the development of a small ferromagnetic component in TbNi2B2C along with the antiferromagnetic ordering at 15.5 K