Gu Yanhong, Liu Zhaoyu, Xie Tao, Zhang Wenliang, Gong Dongliang, Hu Ding, Ma Xiaoyan, Li Chunhong, Zhao Lingxiao, Lin Lifang, Xu Zhuang, Tan Guotai, Chen Genfu, Meng Zi Yang, Yang Yi-Feng, Luo Huiqian, Li Shiliang
Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China.
School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 100190, China.
Phys Rev Lett. 2017 Oct 13;119(15):157001. doi: 10.1103/PhysRevLett.119.157001.
High-temperature superconductivity is closely adjacent to a long-range antiferromagnet, which is called a parent compound. In cuprates, all parent compounds are alike and carrier doping leads to superconductivity, so a unified phase diagram can be drawn. However, the properties of parent compounds for iron-based superconductors show significant diversity and both carrier and isovalent dopings can cause superconductivity, which casts doubt on the idea that there exists a unified phase diagram for them. Here we show that the ordered moments in a variety of iron pnictides are inversely proportional to the effective Curie constants of their nematic susceptibility. This unexpected scaling behavior suggests that the magnetic ground states of iron pnictides can be achieved by tuning the strength of nematic fluctuations. Therefore, a unified phase diagram can be established where superconductivity emerges from a hypothetical parent compound with a large ordered moment but weak nematic fluctuations, which suggests that iron-based superconductors are strongly correlated electron systems.
高温超导与一种长程反铁磁体紧密相邻，这种反铁磁体被称为母体化合物。在铜酸盐中，所有母体化合物都是相似的，载流子掺杂会导致超导性，因此可以绘制出统一的相图。然而，铁基超导体的母体化合物性质表现出显著的多样性，载流子掺杂和同价掺杂都能导致超导性，这使得关于它们存在统一相图的观点受到质疑。在此我们表明，各种铁基氮化物中的有序磁矩与其向列型磁化率的有效居里常数成反比。这种意外的标度行为表明，铁基氮化物的磁基态可以通过调节向列型涨落的强度来实现。因此，可以建立一个统一的相图，其中超导性从具有大有序磁矩但弱向列型涨落的假设母体化合物中出现，这表明铁基超导体是强关联电子系统。
