Tomassucci G, Tortora L, Pugliese G M, Stramaglia F, Simonelli L, Marini C, Terashima K, Wakita T, Ayukawa S, Yokoya T, Kudo K, Nohara M, Mizokawa T, Saini N L
Dipartimento di Fisica, Universitá di Roma "La Sapienza" - P. le Aldo Moro 2, 00185 Roma, Italy.
Microscopy and Magnetism Group, Swiss Light Source, Paul Scherrer Institut, Villigen, Switzerland.
Phys Chem Chem Phys. 2023 Mar 1;25(9):6684-6692. doi: 10.1039/d3cp00004d.
We have combined the extended X-ray absorption fine structure (EXAFS) and X-ray emission spectroscopy (XES) to investigate the local structure and the local iron magnetic moments of (LiFe)OHFeSe (∼0.2) superconductors. The local structure, studied by Fe K-edge EXAFS measurements, is found to be inhomogeneous that is characterized by different Fe-Se bond lengths. The inhomogeneous phase exhibits a peculiar temperature dependence with lattice anomalies in the local structural parameters at the critical temperature (36 K) and at the spin density wave (SDW) transition temperature (130 K). Fe Kβ XES shows iron to be in a low spin state with the local Fe magnetic moment evolving anomalously as a function of temperature. Apart from a quantitative measurement of the local structure of (LiFe)OHFeSe, providing direct evidence of nanoscale inhomogeneity, the results provide further evidence of the vital role that the coupled electronic, lattice and magnetic degrees of freedom play in the iron-based superconductors.
我们结合了扩展X射线吸收精细结构（EXAFS）和X射线发射光谱（XES）来研究(LiFe)OHFeSe（约0.2）超导体的局部结构和局部铁磁矩。通过Fe K边EXAFS测量研究发现，其局部结构是不均匀的，其特征在于不同的Fe - Se键长。这种不均匀相表现出一种特殊的温度依赖性，在临界温度（36 K）和自旋密度波（SDW）转变温度（130 K）时，局部结构参数存在晶格异常。Fe Kβ XES表明铁处于低自旋状态，局部铁磁矩随温度异常变化。除了对(LiFe)OHFeSe的局部结构进行定量测量，提供纳米级不均匀性的直接证据外，这些结果还进一步证明了电子、晶格和磁自由度的耦合在铁基超导体中所起的关键作用。
