Electronic phase transition and an anomalous ordered phase in Ba₂Ti₁₃O₂₂ with 3d¹ ions on a triangle-based lattice

K. Takayama, T. Koyama, S. Mori, K. Kato, M. Takata, J. Fujioka, Y. Tokura, J. Miyazaki, and T. Katsufuji

Accepted Tuesday Apr 16, 2013

We found that Ba$_{2}$Ti$_{13}$O$_{22}$ with Ti$^{3+}$ ($3d^{1}$) ions on a triangle-based lattice exhibits a phase transition at $T_{c} \sim 200$ 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 chare-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.