Department of Physics, Pohang University of Science and Technology, Pohang, 790-784, Korea.
Center for Artificial Low Dimensional Electronic Systems, Institute for Basic Science, Pohang, 790-784, Korea.
Nat Commun. 2017 Dec 18;8(1):2167. doi: 10.1038/s41467-017-02327-0.
A subtle balance between competing interactions in iron-based superconductors (FeSCs) can be tipped by additional interfacial interactions in a heterostructure, often inducing exotic phases with unprecedented properties. Particularly when the proximity-coupled layer is magnetically active, rich phase diagrams are expected in FeSCs, but this has not been explored yet. Here, using high-accuracy As and V nuclear magnetic resonance measurements, we investigate an electronic phase that emerges in the FeAs layer below T ~ 155 K of SrVOFeAs, a naturally assembled heterostructure of an FeSC and a Mott-insulating vanadium oxide. We find that frustration of the otherwise dominant Fe stripe and V Neel fluctuations via interfacial coupling induces a charge/orbital order in the FeAs layers, without either static magnetism or broken C symmetry, while suppressing the Neel antiferromagnetism in the SrVO layers. These findings demonstrate that the magnetic proximity coupling stabilizes a hidden order in FeSCs, which may also apply to other strongly correlated heterostructures.
在铁基超导体 (FeSCs) 中，竞争相互作用之间的微妙平衡可以通过异质结构中的额外界面相互作用来打破，这通常会诱导出具有前所未有的性质的奇特相。特别是当临近耦合层具有磁性活性时，FeSCs 中有望出现丰富的相图，但这尚未得到探索。在这里，我们使用高精度的 As 和 V 核磁共振测量，研究了 SrVOFeAs 中 FeAs 层在 T ~ 155 K 以下出现的一种电子相，SrVOFeAs 是 FeSC 和莫特绝缘氧化钒的自然组装异质结构。我们发现，通过界面耦合对原本占主导地位的 Fe 条纹和 V Neel 涨落的干扰，在没有静态磁性或 C 对称性破缺的情况下，诱导 FeAs 层中的电荷/轨道有序，同时抑制 SrVO 层中的 Neel 反铁磁有序。这些发现表明，磁性临近耦合稳定了 FeSCs 中的隐藏有序，这也可能适用于其他强关联的异质结构。
