Orbital loop currents in iron-based superconductors
Orbital loop currents in iron-based superconductors
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DOI：
10.1103/physrevb.97.155130
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发表时间：
2018-04-13
影响因子：
3.7
通讯作者：
Schmalian, Joerg
中科院分区：
文献类型：
--
作者：
Klug, Markus;Kang, Jian;Schmalian, Joerg
我们证明了在铁基超导体的相图中通常观察到的反铁磁态必然触发以不同铁三维轨道之间的电荷转移为特征的环路电流。这种效应的根源在于这些材料的滑面对称性和原子自旋轨道耦合的存在，这种耦合在1-Fe布里布鲁因区的X点和Y点上耦合状态。在磁矩与磁有序矢量方向平行的特殊情况下，这是在铁基超导体中最常见的力矩配置，这些环路电流涉及d（xy）轨道和d（yz）轨道（如果力矩沿y轴指向）或d（xz）轨道（如果力矩沿x轴指向）。我们发现轨道环电流的两种主要表现是在pnictide/ chalgen位点出现磁矩和在磁有序态发生轨道选择性带分裂，这两种情况都可以通过实验检测到。我们的研究结果突出了铁基超导体中轨道自由度和自旋自由度之间独特的相互交织，并揭示了一个不寻常的相关相的出现，这可能会影响这些材料的正常状态和超导特性。
We show that the antiferromagnetic state commonly observed in the phase diagrams of the iron-based superconductors necessarily triggers loop currents characterized by charge transfer between different Fe 3d orbitals. This effect is rooted on the glide-plane symmetry of these materials and on the existence of an atomic spin-orbit coupling that couples states at the X and Y points of the 1-Fe Brillouin zone. In the particular case in which the magnetic moments are aligned parallel to the magnetic ordering vector direction, which is the moment configuration most commonly found in the iron-based superconductors, these loop currents involve the d(xy) orbital and either the d(yz) orbital (if the moments point along the y axis) or the d(xz) orbitals (if the moments point along the x axis). We show that the two main manifestations of the orbital loop currents are the emergence of magnetic moments in the pnictide/chalcogen site and an orbital-selective band splitting in the magnetically ordered state, both of which could be detected experimentally. Our results highlight the unique intertwining between orbital and spin degrees of freedom in the iron-based superconductors, and reveal the emergence of an unusual correlated phase that may impact the normal state and superconducting properties of these materials.