Spontaneous orbital polarization in the nematic phase of FeSe
Spontaneous orbital polarization in the nematic phase of FeSe
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DOI：
10.1038/s41563-023-01585-2
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发表时间：
2023-06
期刊：
影响因子：
41.2
通讯作者：
C. Occhialini;Joshua J. Sanchez;Q. Song;G. Fabbris;Yongseong Choi;Jong-Woo Kim;P. Ryan;R. Comin
中科院分区：
文献类型：
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作者：
C. Occhialini;Joshua J. Sanchez;Q. Song;G. Fabbris;Yongseong Choi;Jong-Woo Kim;P. Ryan;R. Comin
FeSe中向列性的起源仍然是理解接近向列序的非常规超导性的关键问题。为了理解是什么驱动向列性，确定哪个电子自由度允许独立于结构畸变的自发序参数是至关重要的。在这里，我们使用Fe - K预边缘的x射线线性二色性来测量作为向列相变中原位施加应力和温度的函数的3位占位的各向异性。随着使用x射线衍射来精确量化应变状态，我们揭示了向列相内晶格无关的，自发有序的轨道极化，以及随着从上面接近跃迁而发散的轨道极化率。这些结果有力地证明了自发轨道极化是向列相的主要阶参量。
The origin of nematicity in FeSe remains a critical outstanding question towards understanding unconventional superconductivity in proximity to nematic order. To understand what drives the nematicity, it is essential to determine which electronic degree of freedom admits a spontaneous order parameter independent from the structural distortion. Here we use X-ray linear dichroism at the Fe K pre-edge to measure the anisotropy of the 3dorbital occupation as a function of in situ applied stress and temperature across the nematic transition. Along with using X-ray diffraction to precisely quantify the strain state, we reveal a lattice-independent, spontaneously ordered orbital polarization within the nematic phase, as well as an orbital polarizability that diverges as the transition is approached from above. These results provide strong evidence that spontaneous orbital polarization serves as the primary order parameter of the nematic phase.