Structure and magnetic properties of Ba9V3Te15 with ferromagnetic spin chains

Here we report a ferromagnetic compound ${\mathrm{Ba}}_{9}{\mathrm{V}}_{3}{\mathrm{Te}}_{15}$ with quasi-one-dimensional (1D) spin chains. It was synthesized at high-temperature and high-pressure conditions and systematically investigated via structural, transport, magnetic and heat capacity measurements. ${\mathrm{Ba}}_{9}{\mathrm{V}}_{3}{\mathrm{Te}}_{15}$ mainly consists of trimerized face-sharing $\mathrm{V}{\mathrm{Te}}_{6}$ octahedral chains running along the $c$ axis, which are separated by a distance of $10.184(8)\phantom{\rule{0.28em}{0ex}}\AA{}$, thus demonstrating a strong 1D structural character. ${\mathrm{Ba}}_{9}{\mathrm{V}}_{3}{\mathrm{Te}}_{15}$ is a semiconductor with a band gap $\ensuremath{\sim}128\phantom{\rule{0.28em}{0ex}}\mathrm{meV}$ and undergoes a ferromagnetic transition with ${T}_{\mathrm{C}}\ensuremath{\sim}3.6\phantom{\rule{0.28em}{0ex}}\mathrm{K}$. Far above ${T}_{\mathrm{C}}$, the short-range spin orders due to the intrachain spin coupling have developed, which leads to a negative magnetoresistance effect, the deviation of magnetic susceptibility from the Curie-Weiss law and ${T}^{1/2}$ dependence of magnetic heat capacity. Our results reveal that ${\mathrm{Ba}}_{9}{\mathrm{V}}_{3}{\mathrm{Te}}_{15}$ provides a good opportunity to study the intrinsic properties of a system with quasi-1D ferromagnetic spin chains.