Massat Pierre, Farina Donato, Paul Indranil, Karlsson Sandra, Strobel Pierre, Toulemonde Pierre, Méasson Marie-Aude, Cazayous Maximilien, Sacuto Alain, Kasahara Shigeru, Shibauchi Takasada, Matsuda Yuji, Gallais Yann
Laboratoire Matériaux et Phénomènes Quantiques, CNRS UMR7162, Université Paris Diderot, Paris Cedex 13, France;
Institut Néél, CNRS Unité Propre de Recherche 2940, 38042 Grenoble, France; Institut Néél, Université Grenoble Alpes, 38042 Grenoble, France;
Proc Natl Acad Sci U S A. 2016 Aug 16;113(33):9177-81. doi: 10.1073/pnas.1606562113. Epub 2016 Aug 1.
The spontaneous appearance of nematicity, a state of matter that breaks rotation but not translation symmetry, is one of the most intriguing properties of the iron-based superconductors (Fe SC), and has relevance for the cuprates as well. Establishing the critical electronic modes behind nematicity remains a challenge, however, because their associated susceptibilities are not easily accessible by conventional probes. Here, using FeSe as a model system, and symmetry-resolved electronic Raman scattering as a probe, we unravel the presence of critical charge nematic fluctuations near the structural/nematic transition temperature, [Formula: see text] 90 K. The diverging behavior of the associated nematic susceptibility foretells the presence of a Pomeranchuk instability of the Fermi surface with d-wave symmetry. The excellent scaling between the observed nematic susceptibility and elastic modulus data demonstrates that the structural distortion is driven by this d-wave Pomeranchuk transition. Our results make a strong case for charge-induced nematicity in FeSe.
向列性（一种破坏旋转对称性但不破坏平移对称性的物质状态）的自发出现是铁基超导体（Fe SC）最引人入胜的特性之一，对铜酸盐超导体也具有重要意义。然而，确定向列性背后的关键电子模式仍然是一项挑战，因为它们相关的磁化率不容易通过传统探针获取。在这里，我们以FeSe为模型体系，利用对称性分辨电子拉曼散射作为探针，揭示了在结构/向列相变温度（约90 K）附近存在临界电荷向列涨落。相关向列磁化率的发散行为预示着费米面存在具有d波对称性的波梅兰丘克不稳定性。观察到的向列磁化率与弹性模量数据之间的良好标度关系表明，结构畸变是由这种d波波梅兰丘克转变驱动的。我们的结果有力地证明了FeSe中电荷诱导的向列性。
