基于三带模型研究竞争序对铁基超导体中涡旋态的影响

项目名称： 基于三带模型研究竞争序对铁基超导体中涡旋态的影响

项目编号： No.11504379

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： 王景荣

作者单位： 中国科学院合肥物质科学研究院

项目金额： 20万元

中文摘要： 对于铁基超导体的研究是目前凝聚态物理最重要的领域之一。随着掺杂浓度、压力等因素的变化，铁基超导体表现出自旋密度波（SDW）态、nematic电子态、超导态等不同的相。研究SDW序、nematic序和超导序的竞争与共存有助于理解铁基超导体的配对机制。我们将基于三带模型，在费米子色散关系中引入磁场影响，推导包含了磁场的关于SDW序、nematic序和超导序的有效作用量，然后根据该有效作用量研究SDW序和nematic序对于涡旋态的影响。我们希望解决两方面的问题：第一，随着化学势等参数的调节，SDW序、nematic序和超导序在涡旋态中能否同时存在，如果同时存在，是处于相分离状态还是微观共存状态；第二，竞争序的量子涨落将会对涡旋态带来何种影响。通过这些研究可以丰富和加深对于SDW序、nematic序和超导序竞争与共存的理解，并更好地解释或者预测铁基超导体中关于涡旋态的实验结果。

中文关键词： 铁基超导体；竞争序；涡旋态；向列序；量子涨落

英文摘要： Study of iron based superconductors is one of the most important fields in the condensed matter physics currently. With the changing of doping, pressure, etc, iron based superconductors exhibit different phases, including spin density wave (SDW) phase, electronic nematic phase and superconducting phase, etc. The study of the competition and coexistence of SDW order, nematic order and superconducting order is helpful for understanding the pairing mechanism of iron based superconductors. Based on the three-band model, we impose the influence of magnetic field to the dispersion relation of the fermions, and derive the effective action about SDW order, nematic order and superconducting order. Then we will study the influence of SDW order and nematic order on the vortex state through this effective action. We will resolve questions in two aspects. First, whether or not the SDW order, nematic order and superconducting order can coexist in the vortex state with the adjusting of parameters such as chemical potential, etc. If they can coexist, whether they are phase separation or microscopic coexistence. Second, how the quantum fluctuation of the competing orders influences on the vortex state. These studies will give more insight for the competition and coexistence of SDW order, nematic order and superconducting order. We also expect that these studies will be helpful for a better understanding on the experimental results or predict some new interesting experimental results about the vortex state in the iron based superconductors.

英文关键词： iron based superconductors;competing orders ;vortex state ;nematic order;quantum fluctuation