Structure and magnetic states of R2AgIn3 (R = Pr, Nd, Tb, Ho, Er) intermetallics

Complete text of publication follows. Neutron power diffraction has been applied to the study of structure and magnetic properties of ternary intermetallic rare earth (R)-silver-indium compounds. R2AgIn3 (R = Nd, Tb, Ho, Er) crystallize in the hexagonal CaIn2-type structure in space group P63/mmc. The unit cells contain one formula unit each with R on 2b sites (0,0,1/4) and Ag and In statistically distributed on 4f sites (1/3,2/3,z). The lattice and atomic position parameters have been refined. Interatomic distances are discussed with respect to the stability criteria of the CaIn2-type structure. Additional peaks in the diffraction pattern of Pr2AgIn3 indicate the occurrence of a modified structure. Low temperature neutron diffraction experiments down to 1.5 K have been in addition to previous macroscopic susceptibility measurements indicating antiferromagnetic behaviour as well as irreversibilities and substantial differences between zero and non-zero field susceptibility curves. Neutron diffraction reveals a collinear antiferromagnetic structure in Tb2AgIn3 below 42 K. No long range magnetic order, however, has been found in the other compounds. The non-existence of long range ordered R moments is attributed to spin glass similar states originating from frustration effects due to the structural disorder. The magnetic behaviour of theses compounds is strongly influenced by magnetocrystalline anisotropies. (author)