铁基超导体中自旋轨道耦合效应的微观理论研究

项目名称： 铁基超导体中自旋轨道耦合效应的微观理论研究

项目编号： No.11504085

项目类型： 青年科学基金项目

立项/批准年度： 2016

项目学科： 数理科学和化学

项目作者： 向圆圆

作者单位： 河海大学

项目金额： 20万元

中文摘要： 一直以来，铁基超导体中的自旋轨道耦合效应都被认为可以忽略。然而，近期的光电子光谱和中子散射实验却直接观测到了这种效应的存在，包括能带的自旋劈裂和降温时铁自旋极化的重新取向。结合先前实验观测到“122”体系自旋激发谱的各向异性以及LiFeAs中可能的三态配对，有理由认为完整描述铁基超导体可能需要考虑自旋轨道耦合。本项目拟从包含自旋轨道耦合的微观晶格模型出发，采用无规相近似和泛函重整化群方法，研究自旋轨道耦合对铁基超导体磁性和超导性质的影响，包括：（1）通过计算正常态静态极化自旋磁化率得到静态的自旋极化取向；（2）通过泛函重整化群计算得到超导配对对称性和配对算符的微观表达形式；（3）超导态物性计算，包括自旋激发谱、准粒子散射相干谱、开边界体系的Bogoliubov-de Gennes能带等。这些理论研究有可能解释不同实验中观测到的奇异现象，促进更为完整的铁基超导体理论描述。

中文关键词： 铁基超导体；自旋轨道耦合；配对对称性；多带电子体系；自旋极化

英文摘要： Spin-orbit coupling was always thought to be unimportant in iron-based superconductors. However, recent angle-resolved photoemission spectroscopy and neutron scattering experiments directly observe its effects, including spin-splitting of the energy bands and reorientation of iron spins at lower temperature. Combined with earlier experimental observation of anisotropic spin excitation spectra and possible triplet pairing, it's reasonable to take spin-orbit coupling into consideration for a full description of iron-based superconductors. Starting with microscopic lattice models with spin-orbit coupling and applying the random phase approximation and functional renormalization group method, this project is going to study the effects of spin-orbit coupling on the magnetic and superconducting properties of iron-based superconductors. The studies include: (1)static spin-orientation through calculations of static polarized spin susceptibilities; (2)pairing symmetry and microscopic pairing form through functional renormalization group studies; (3)calculations of physical properties in the superconducting state, such as spin excitation spectra for different spin polarizations, quasi-particle scattering interference spectra, the Bogoliubov-de Gennes bands of an open-bounded system, etc. These theoretical studies may explain the many exotic and inconsistent experimental observations and promote the full theoretical description of iron-based superconductors.

英文关键词： iron-based superconductor;spin-orbit coupling;pairing symmetry;multi-band system;spin polarization