Department of Physics, Chiba University, Chiba 263-8522, Japan.
Phys Rev Lett. 2011 Dec 23;107(26):266402. doi: 10.1103/PhysRevLett.107.266402. Epub 2011 Dec 20.
Synchrotron x-ray diffraction experiment shows that the metal-insulator transition occurring in a ferromagnetic state of a hollandite K(2)Cr(8)O(16) is accompanied by a structural distortion from the tetragonal I4/m to monoclinic P112(1)/a phase with a √2×√2×1 supercell. Detailed electronic structure calculations demonstrate that the metal-insulator transition is caused by a Peierls instability in the quasi-one-dimensional column structure made of four coupled Cr-O chains running in the c direction, leading to the formation of tetramers of Cr ions below the transition temperature. This provides a rare example of the Peierls transition of fully spin-polarized electron systems.
同步辐射 X 射线衍射实验表明，在方钴矿 K(2)Cr(8)O(16)的铁磁态中发生的金属-绝缘体转变伴随着从四方 I4/m 到单斜 P112(1)/a 相的结构畸变，具有√2×√2×1 超胞。详细的电子结构计算表明，金属-绝缘体转变是由准一维柱状结构中四个耦合的 Cr-O 链在 c 方向上的佩尔斯不稳定性引起的，导致在转变温度以下形成 Cr 离子的四聚体。这为完全自旋极化电子系统的佩尔斯转变提供了一个罕见的例子。
