The study on the mechanism of ferromagnetic metal-insulator transition and novel quantum properties in chromium oxides

通过同步辐射X射线衍射实验和电子结构计算对K2 Cr 8 O 16的结构进行了详细的分析，结果表明，K2 Cr 8 O 16的铁磁金属-绝缘体转变是由于在c方向上的四条耦合Cr-O链组成的准一维柱状结构中的Peierls不稳定性导致的，在低于转变温度时，Cr离子的四聚体形成.这提供了完全自旋极化电子系统的佩尔斯跃迁的罕见例子。

Detailed structure analysis by synchrotron x-ray diffraction experiments and the electronic structure calculations demonstrate that the novel ferromagnetic metal-insulator transition in K2Cr8O16 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.