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arXiv · 1111.3389

Peierls Mechanism of the Metal-Insulator Transition in Ferromagnetic Hollandite K2Cr8O16

T. Toriyama·A. Nakao·Y. Yamaki·H. Nakao·Y. Murakami·K. Hasegawa·M. Isobe·Y. Ueda·A. V. Ushakov·D. I. Khomskii·S. V. Streltsov·T. Konishi·Y. Ohta
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Abstract

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 $\sqrt{2}\times\sqrt{2}\times 1$ 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 furnishes a rare example of the Peierls transition of fully spin-polarized electron systems.

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T. Toriyama, A. Nakao, Y. Yamaki, H. Nakao, Y. Murakami, K. Hasegawa, M. Isobe, Y. Ueda, A. V. Ushakov, D. I. Khomskii, S. V. Streltsov, T. Konishi, Y. Ohta. 2011-11-14. Peierls Mechanism of the Metal-Insulator Transition in Ferromagnetic Hollandite K2Cr8O16. https://doi.org/10.1103/physrevlett.107.266402

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