Division of Materials Sciences and Engineering, Ames Laboratory, U.S. DOE, Iowa State University, Ames, Iowa 50011, USA.
Department of Physics and Astronomy, Iowa State University, Ames, Iowa 50011, USA.
Nat Commun. 2016 Sep 1;7:12728. doi: 10.1038/ncomms12728.
A hallmark of the iron-based superconductors is the strong coupling between magnetic, structural and electronic degrees of freedom. However, a universal picture of the normal state properties of these compounds has been confounded by recent investigations of FeSe where the nematic (structural) and magnetic transitions appear to be decoupled. Here, using synchrotron-based high-energy x-ray diffraction and time-domain Mössbauer spectroscopy, we show that nematicity and magnetism in FeSe under applied pressure are indeed strongly coupled. Distinct structural and magnetic transitions are observed for pressures between 1.0 and 1.7 GPa and merge into a single first-order transition for pressures ≳1.7 GPa, reminiscent of what has been found for the evolution of these transitions in the prototypical system Ba(Fe1-xCox)2As2. Our results are consistent with a spin-driven mechanism for nematic order in FeSe and provide an important step towards a universal description of the normal state properties of the iron-based superconductors.
铁基超导体的一个特点是磁、结构和电子自由度之间的强耦合。然而，最近对 FeSe 的研究使这些化合物的正常态性质的普遍图景变得复杂，因为在 FeSe 中，向列（结构）和磁转变似乎是解耦的。在这里，我们使用基于同步加速器的高能 X 射线衍射和时域穆斯堡尔光谱学，表明在施加压力下，FeSe 中的向列性和磁性确实是强耦合的。在 1.0 到 1.7 GPa 之间的压力下观察到明显的结构和磁转变，并且在压力≳1.7 GPa 时合并为单个一级转变，类似于在原型系统 Ba(Fe1-xCox)2As2 中发现的这些转变的演化。我们的结果与 FeSe 中向列序的自旋驱动机制一致，并为铁基超导体的正常态性质的普遍描述提供了重要的一步。
