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arXiv · 1102.3674

Superconductivity tuned by the iron vacancy order in K$_{\bf x}$Fe$_{\bf 2-y}$Se$_2$

Wei Bao·G. N. Li·Q. Huang·G. F. Chen·J. B. He·M. A. Green·Y. Qiu·D. M. Wang·J. L. Luo
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Abstract

Combining in-depth neutron diffraction and systematic bulk studies, we discover that the $\sqrt{5}\times\sqrt{5}$ Fe vacancy order with its associated block antiferromagnetic order is the ground state, with varying occupancy ratio of the iron 16i and vacancy 4d sites, across the phase-diagram of K$_{\bf x}$Fe$_{\bf 2-y}$Se$_2$. The orthorhombic order with one of the four Fe sites vacant appears only at intermediate temperature as a competing phase. The material experiences an insulator to metal crossover when the $\sqrt{5}\times\sqrt{5}$ order has highly developed. Superconductivity occurs in such a metallic phase.

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Wei Bao, G. N. Li, Q. Huang, G. F. Chen, J. B. He, M. A. Green, Y. Qiu, D. M. Wang, J. L. Luo. 2011-02-17. Superconductivity tuned by the iron vacancy order in K$_{\bf x}$Fe$_{\bf 2-y}$Se$_2$. https://doi.org/10.1016/j.physc.2011.12.001

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