We found that ${\mathrm{Ba}}_2{\mathrm{Ti}}_{13}{\mathrm{O}}_{22}$ with ${\mathrm{Ti}}^{3+}$ ($3d^1$) ions on a triangle-based lattice exhibits a phase transition at $T_c\sim 200\mathrm{K}$, below which the increase of electrical resistivity and decrease of magnetic susceptibility were observed. Transmission electron microscopy and optical reflectivity measurements indicate that the low-temperature phase of the present compound shares characteristics in common with a charge-density-wave state with remnant carriers, although a commensurate wave vector of the modulation and a linear temperature dependence of the magnetic susceptibility below $T_c$ suggest an exotic ordered state.

• Received 12 February 2013

DOI:https://doi.org/10.1103/PhysRevLett.110.196405