Spin excitations in a model of FeSe with orbital ordering
Spin excitations in a model of FeSe with orbital ordering
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DOI：
10.1103/physrevb.92.224515
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发表时间：
2015-12-28
影响因子：
3.7
通讯作者：
Andersen, Brian M.
中科院分区：
文献类型：
--
作者：
Kreisel, A.;Mukherjee, Shantanu;Andersen, Brian M.
我们提出了一个理论研究的动态自旋磁化率的有趣的铁基超导体FeSe，紧束缚模型的基础上开发的温度相关的能带结构在这个系统中。该模型允许在结构转变下方的d（xz）/d（yz）通道中进行轨道有序化，并且在低温下呈现出强烈的C-4-非对称性破坏的费米表面，这解释了该材料的非对称性。计算的自旋激发峰值波矢量（π，0）在1-Fe布里渊区，与广泛的最大能量的顺序为几毫电子伏。在这个范围内，超导性的出现使能量峰值变尖，产生了（π，0）“中子共振”，如最近的实验所见。除了相当低的能量尺度的这些波动，这些结果是大致类似的标准行为在Fe磷属元素化物系统。然而，在更高的能量下，强度增加并沿（pi，0）-（pi，pi）线沿着向波矢量移动。与现有的非弹性中子实验和核磁共振数据进行了比较，并对进一步的研究进行了预测。
We present a theoretical study of the dynamical spin susceptibility for the intriguing Fe-based superconductor FeSe, based on a tight-binding model developed to account for the temperature-dependent band structure in this system. The model allows for orbital ordering in the d(xz)/d(yz) channel below the structural transition and presents a strongly C-4-symmetry-broken Fermi surface at low temperatures which accounts for the nematic properties of this material. The calculated spin excitations are peaked at wave vector (pi, 0) in the 1-Fe Brillouin zone, with a broad maximum at energies of order a few meV. In this range, the occurrence of superconductivity sharpens this peak in energy, creating a (pi, 0) "neutron resonance" as seen in recent experiments. With the exception of the quite low energy scale of these fluctuations, these results are roughly similar to standard behavior in Fe pnictide systems. At higher energies, however, intensity increases and shifts to wave vectors along the (pi, 0)-(pi, pi) line. We compare with existing inelastic neutron experiments and NMR data, and give predictions for further studies.