Momentum-dependent sign inversion of orbital order in superconducting FeSe
Momentum-dependent sign inversion of orbital order in superconducting FeSe
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DOI：
10.1103/physrevb.92.205117
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发表时间：
2015-11-13
影响因子：
3.7
通讯作者：
Ishizaka, K.
中科院分区：
文献类型：
--
作者：
Suzuki, Y.;Shimojima, T.;Ishizaka, K.
我们研究了电子重建四方正交结构转变的FeSe采用偏振相关的角度分辨光电子能谱解孪晶单晶。在整个结构转变过程中，由于d（xz）/d（yz）轨道简并度的提升，伽马点和M点周围的电子结构从四重对称修改为二重对称。d（xz）带在Gamma点处向上移动，而在M点处向下移动，表明正交FeSe的电子结构具有动量相关的变号轨道极化。由于这种符号变化的轨道顺序，在伽马点和M点处的椭圆费米面的伸长方向相对于彼此旋转90度，这使得这些FS之间的嵌套条件不完美。目前的结果，支持的计算，表明可能抑制的自旋涨落介导的超导性在正交FeSe，相比，轨道有序状态没有符号的变化。
We investigate the electronic reconstruction across the tetragonal-orthorhombic structural transition in FeSe by employing polarization-dependent angle-resolved photoemission spectroscopy on detwinned single crystals. Across the structural transition, the electronic structures around the Gamma and M points are modified from fourfold to twofold symmetry due to the lifting of degeneracy in d(xz)/d(yz) orbitals. The d(xz) band shifts upward at the Gamma point, while it moves downward at the M point, suggesting that the electronic structure of orthorhombic FeSe is characterized by a momentum-dependent sign-changing orbital polarization. Due to this sign-changing orbital order, the elongated directions of the elliptical Fermi surfaces at the Gamma and M points are rotated by 90 degrees with respect to each other, which makes the nesting condition between these FSs imperfect. The present result, supported by calculations, indicates the possible suppression of the spin-fluctuation mediated superconductivity in the orthorhombic FeSe, as compared to the orbital-ordered state without sign change.