The structural and magnetic properties of BaMn${}_2$Si${}_2$O${}_7$ have been investigated. The magnetic susceptibility and specific heat, measured using single crystals, suggest that the quasi-one-dimensional magnetism originating from the loosely coupled Mn${}^{2+}$ chain carrying $S=5/2$ is present at high temperatures, which is similar to the other quasi-one-dimensional barium silicates, Ba$M$${}_2$Si${}_2$O${}_7$ ($M$: Cu and Co). The Néel temperature ($T_{\mathrm{N}}\sim 26$ K) is high compared to the magnetic interaction along the chain ($J=-6$ K). Neutron powder diffraction study has revealed that the magnetic structure is long ranged with antiferromagnetic arrangement along the chain ($c$) direction and ferromagnetic arrangement along the $a$ and $b$ axes. Detailed structural analysis suggests that the interchain interaction via Mn-O-Mn bond along the $a$ axis is relatively large, which makes the system behave more two-dimensionally in the $ac$ plane and enhances $T_{\mathrm{N}}$.

• Received 18 July 2013

DOI:https://doi.org/10.1103/PhysRevB.88.144405