Magnetic structure of RCo2Ge2 (R=Ho,Tb), a neutron diffraction study

A study of the magnetic structure of RCo2Ge2 (I4/mmm) with R=Tb, Ho was performed using neutron diffraction of powder samples. The 4.2 K diffraction patterns reveal a type I antiferromagnetic structure on the R sublattice. The magnetic moments lie along c, being 8.84β and 8.12β for Tb and Ho respectively. The possibility of order on the Co sublattice was also investigated, and the magnetic moment was found to be not larger then 0.12β (in TbCo2Ge2) and 1.7β (in HoCo2Ge2). The Neel temperatures are 31 K and 8.5 K respectively.