New Superconductivity Dome in LaFeAsO 1 −x F x Accompanied by Structural Transition
New Superconductivity Dome in LaFeAsO 1 −x F x Accompanied by Structural Transition
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DOI：
10.1088/0256-307x/32/10/107401
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发表时间：
2015-07
影响因子：
3.5
通讯作者：
J. Yang;R. Zhou;L. L. Wei-L.;H. Yang;J. Li;Z. Zhao;G. Zheng
中科院分区：
文献类型：
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作者：
J. Yang;R. Zhou;L. L. Wei-L.;H. Yang;J. Li;Z. Zhao;G. Zheng
高温超导常出现在反铁磁性附近。LaFeAsO1−xFx（x ≤ 0.2）和许多其他铁基超导体也是如此，这导致了超导性是由与附近磁性相关的波动介导的建议。本文报道了在LaFeAsO1−xFx（0.25 ≤ x ≤ 0.75）中发现的一个新的无低能磁涨落的超导圆顶，其中在xopt = 0.5−0.55处的最大临界温度Tc甚至高于x ≤ 0.2处的临界温度Tc。通过核磁共振和透射电子显微镜研究表明，当x > 0.5时，在Tc以上发生了C4转动破缺结构转变。我们的结果指出了一个新的高温超导范例。
High-temperature superconductivity is often found in the vicinity of antiferromagnetism. This is also true in LaFeAsO1−xFx (x ≤ 0.2) and many other iron-based superconductors, which leads to proposals that superconductivity is mediated by fluctuations associated with the nearby magnetism. Here we report the discovery of a new superconductivity dome without low-energy magnetic fluctuations in LaFeAsO1−xFx with 0.25 ≤ x ≤ 0.75, where the maximal critical temperature Tc at xopt = 0.5−0.55 is even higher than that at x ≤ 0.2. By nuclear magnetic resonance and transmission electron microscopy, we show that a C4 rotation symmetry-breaking structural transition takes place for x > 0.5 above Tc. Our results point to a new paradigm of high temperature superconductivity.