Center for High Pressure Science and Technology Advanced Research (HPSTAR), 100094, Beijing, China.
HPSynC, Geophysical Laboratory, Carnegie Institution of Washington, Argonne, IL, 60439, USA.
Nat Commun. 2018 May 15;9(1):1914. doi: 10.1038/s41467-018-04326-1.
The discovery of iron-based superconductors (FeSCs), with the highest transition temperature (T) up to 55 K, has attracted worldwide research efforts over the past ten years. So far, all these FeSCs structurally adopt FeSe-type layers with a square iron lattice and superconductivity can be generated by either chemical doping or external pressure. Herein, we report the observation of superconductivity in an iron-based honeycomb lattice via pressure-driven spin-crossover. Under compression, the layered FePX (X = S, Se) simultaneously undergo large in-plane lattice collapses, abrupt spin-crossovers, and insulator-metal transitions. Superconductivity emerges in FePSe along with the structural transition and vanishing of magnetic moment with a starting T ~ 2.5 K at 9.0 GPa and the maximum T ~ 5.5 K around 30 GPa. The discovery of superconductivity in iron-based honeycomb lattice provides a demonstration for the pursuit of transition-metal-based superconductors via pressure-driven spin-crossover.
在过去的十年中，铁基超导体（FeSCs）的发现引起了全球范围内的研究热潮，其最高转变温度（T）高达 55K。到目前为止，所有这些 FeSCs 的结构都采用具有正方形铁晶格的 FeSe 型层，通过化学掺杂或外部压力都可以产生超导性。在此，我们通过压力驱动的自旋交叉报告了在铁基蜂窝晶格中超导性的观察。在压缩下，层状 FePX（X=S，Se）同时经历大的面内晶格坍塌、突然的自旋交叉和绝缘-金属转变。在结构转变和磁矩消失的同时，FePSe 中出现了超导性，起始 T2.5K 出现在 9.0GPa，最大 T5.5K 出现在 30GPa 左右。在铁基蜂窝晶格中超导性的发现为通过压力驱动的自旋交叉来探索过渡金属基超导体提供了一个范例。
