Impact of Dynamic Orbital Correlations on Magnetic Excitations in the Normal State of Iron-Based Superconductors
Impact of Dynamic Orbital Correlations on Magnetic Excitations in the Normal State of Iron-Based Superconductors
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DOI：
10.1103/physrevb.86.094516
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发表时间：
2012-06
影响因子：
3.7
通讯作者：
Wei‐Cheng Lee;W. Lv;J. Tranquada;P. Phillips
中科院分区：
文献类型：
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作者：
Wei‐Cheng Lee;W. Lv;J. Tranquada;P. Phillips
我们在这里表明，轨道自由度产生一个独特的签名以上的磁有序温度的铁基超导体的磁激发谱。由于dxz和dyz轨道与费米表面拓扑结构密切相关，磁激发的性质可以由于静态或波动轨道相关的存在而显着修改。在一个五轨道巡回模型中，我们表明，静态轨道秩序通常会导致增强相称的磁激发，即使原来的费米面缺乏嵌套在（π，0）或（0，π）。当长程轨道序不存在时，超出标准随机相位近似的高斯涨落捕获了涨落轨道相关对磁激发的影响。我们发现，相称的磁激发也可以增强，如果轨道相关性强。我们的结果为最近的中子散射测量中观察到的增度-公度变换提供了一个自然的解释（Z。Xu，et.例如，arXiv：1201.4404），我们提出，这种不寻常的转换是一个重要的签名，以区分轨道和自旋物理在正常状态的pnictides。磁和超导状态的影响进行了讨论。PACS编号：
We show here that orbital degrees of freedom produce a distinct signature in the magnetic excitation spectrum of iron-based superconductors above the magnetic ordering temperature. Because dxz and dyz orbitals are strongly connected with Fermi surface topology, the nature of magnetic excitations can be modified significantly due to the presence of either static or fluctuating orbital correlations. Within a five-orbital itinerant model, we show that static orbital order generally leads to an enhancement of commensurate magnetic excitations even when the original Fermi surface lacks nesting at (π,0) or (0,π). When long-range orbital order is absent, Gaussian fluctuations beyond the standard random-phase approximation capture the effects of fluctuating orbital correlations on the magnetic excitations. We find that commensurate magnetic excitations can also be enhanced if the orbital correlations are strong. Our results offer a natural explanation for the incommensurateto-commensurate transformation observed in a recent neutron scattering measurement (Z. Xu, et. al., arXiv:1201.4404), and we propose that this unusual transformation is an important signature to distinguish orbital from spin physics in the normal state of pnictides. Implications for the magnetic and superconducting states are discussed. PACS numbers: