Magnetic structures of R2RhSi3 (R=Ho, Er) compounds

Powder X-ray and neutron diffraction and magnetic measurements have been performed on R₂RhSi₃ (R=Ho and Er) compounds at low temperatures. The compounds crystallize in a derivative of the hexagonal AlB₂-type structure. The crystal structure parameters have been refined on the basis of the X-ray and neutron diffraction patterns collected in the paramagnetic region. These compounds are antiferromagnets with Néel temperatures of 5.2 K for Ho₂RhSi₃ and 5 K for Er₂RhSi₃. Both compounds exhibit collinear magnetic structures, described by the propagation vector k=(1/2,0,0) for Ho₂RhSi₃ and k=(0,0,0) for Er₂RhSi₃. This magnetic order is stable in the temperature range between 1.5 K and the Néel temperature.