Antiferromagnetic three-sublattice Tb ordering inTb14Ag51

Abstract

Bulk magnetic, x-ray, and neutron-diffraction measurements were performed on polycrystalline ${\mathrm{Tb}}_{14}{\mathrm{Ag}}_{51}$ in the temperature range from $1.5\phantom{\rule{0.3em}{0ex}}\mathrm{K}$ to room temperature. Its chemical ${\mathrm{Gd}}_{14}{\mathrm{Ag}}_{51}$-type structure corresponding to space group $P6∕m$ has been refined at 300 and at $30\phantom{\rule{0.3em}{0ex}}\mathrm{K}$. Combined with group-theoretical symmetry analysis, we show that the magnetic structure of this intermetallic compound is of a different $\mathbf{k}=(1∕3,1∕3,0)$ type with three magnetic Tb sublattices ordering simultaneously below ${T}_{\mathrm{N}}=27.5(5)\phantom{\rule{0.3em}{0ex}}\mathrm{K}$ according to the combined irreducible representations ${\ensuremath{\tau}}_{4}$ and ${\ensuremath{\tau}}_{6}$.