Nematicity in LaFeAsO1−xFx-猫眼课题宝

DOI：

10.1002/pssb.201600214

发表时间：

2016-04

期刊：

physica status solidi (b)

影响因子：

通讯作者：

中科院分区：

其他

文献类型：

作者：

C. Hess;C. Hess;H. Grafe;A. Kondrat;G. Lang;G. Lang;F. Hammerath;F. Hammerath;L. Wang;R. Klingeler;G. Behr;B. Büchner;B. Büchner

轨道有序是近年来在铁基超导体中出现的另一种重要状态，它对超导电性的作用以及它与磁序和正交晶格扭曲的关系一直备受争议。为了寻找氧化镍镍矿中这一所谓向列相的特征，我们重新研究了磷锌矿超导体LaFeAsO1−xFx的正常态性质，重点讨论了电阻率、能斯特效应、热膨胀和75作为核磁共振数据。在欠掺杂能级x=0.05时，输运性质在与未掺杂LaFeAsO形成长程向列相有序的温度大致相同的温度下表现出明显的反常，即在160K左右。此外，75AS-核磁共振自旋-晶格弛豫速率(T1T)−1揭示了自旋涨落的逐渐减慢。然而，没有长程磁序和可检测到的正交晶格扭曲。因此，我们从数据中得出结论，在160K附近，近程轨道-向列相有序或缓慢起伏的形式设置，输运中的所有反常以及慢自旋涨落的迹象在最佳掺杂x=0.1时消失，这表明在LaFeAsO_1-−_xFx中，向列相实际上与超导电性竞争。

Orbital ordering has recently emerged as another important state in iron‐based superconductors, and its role for superconductivity as well as its connection to magnetic order and orthorhombic lattice distortion are heavily debated. In order to search for signatures of this so‐called nematic phase in oxypnictides, we revisit the normal state properties of the pnictide superconductor LaFeAsO1−x Fx with a focus on resistivity, Nernst effect, thermal expansion, and 75 As nuclear magnetic resonance (NMR) data. The transport properties at the underdoped level x=0.05 exhibit pronounced anomalies at about the same temperature where undoped LaFeAsO develops long‐range nematic ordering, i.e., at about 160 K. Furthermore, the 75 As‐NMR spin‐lattice relaxation rate (T1T)−1 reveals a progressive slowing down of spin fluctuations. Yet, long‐range magnetic order and also a detectable orthorhombic lattice distortion are absent. Thus, we conclude from the data that short‐range orbital‐nematic ordering or a slowly fluctuating form of it sets in near 160 K. Remarkably, all anomalies in the transport and also the indications of slow spin fluctuations disappear close to optimal doping x=0.1 which suggests that in LaFeAsO1−x Fx the nematic phase actually competes with superconductivity.

Nematicity in LaFeAsO1−xFx

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