Magnetic characterization of the sawtooth-lattice olivines $\mathrm{Zn}{L}_2{\mathrm{S}}_4$ $(L=\mathrm{Er},\mathrm{Tm},\mathrm{Yb})$

We report the magnetic properties of the $\mathrm{Zn}{L}_2{\mathrm{S}}_4$ $(L=\mathrm{Er},\mathrm{Tm},\mathrm{Yb})$ olivines, in which the magnetic lanthanide ions are in a potentially frustrated geometry consisting of sawtooth chains of corner-sharing triangles. Fits to the high-temperature magnetic susceptibility yielded Curie-Weiss temperatures of ${\theta }_W\approx -4$, $-13$, and $-75\mathrm{K}$ for the Er, Tm, and Yb compounds, respectively. None of the compounds displayed magnetic long-range order above $T=1.8\mathrm{K}$. The lack of ordering at temperatures near ${\theta }_W$ may be attributed to either the low dimensionality of the structure or the frustrating effect of the triangular geometry.