Transition from short-range to long-range antiferromagnetic order in single-crystalline CoSb$_2$O$_6$

Single-crystalline CoSb$_2$O$_6$ has been grown via chemical vapor transport. A broad peak in the magnetic susceptibility indicates short-range antiferromagnetic order. Anisotropy among the peak positions suggests a ratio of interchain coupling constants along the \textit{a}- and \textit{c}-axes of $J_a/J_c\sim 1.4$. A second order phase transition to long-range antiferromagnetic order is observed at 13.4 K as an abrupt change in slope. Heat capacity measurements suggest that local 1D magnetic order begins upon cooling below $\sim 70$ K. Thermal expansion measurements also exhibit anisotropic behavior that is affected by the short-range order. Unlike that of the \textit{a}-axis, the thermal expansion coefficient, $\mu$, for the \textit{c}-axis becomes negative below $\sim 70$ K due to anharmonic lattice vibrations resulting from the formation of short-range 1D antiferromagnetic order.