FeSe中二维自旋与轨道涨落的第一性原理研究与介观建模
A first-principles study and mesoscopic modeling of two-dimensional spin and orbital fluctuations in FeSe
AI总结：
本研究采用密度泛函理论计算FeSe性质，探究磁有序对带宽的修正及高压下磁形成能变化，提出场论模型解释二维自旋轨道涨落的非平凡行为及拓扑涡旋的介观效应。
摘要：
我们在广义梯度近似水平下，采用密度泛函理论计算了FeSe的结构、电子和磁学性质。首先，我们研究了费米能级处d带的带宽如何通过添加简单修正（哈伯德U、洪特J）以及引入长程磁有序发生重整化。我们发现，引入条纹状或交错二聚体反铁磁有序，可使广义梯度近似水平下被严重高估的带宽更接近实验观测值。其次，针对铁磁有序、条纹状、棋盘格状及交错二聚体反铁磁有序，我们探究了压力高达6 GPa时，磁形成能随Fe局域磁矩的变化情况。双线性和双二次交换能分别由海森堡模型和非共线第一性原理计算推导得出。我们发现自旋交换参数随磁化强度呈现出非平凡行为，并提出了一个场论模型，该模型从二维自旋和轨道涨落的角度解释了这些结果。这些涨落的特征既可以是标准密度波，也可以是拓扑涡旋。拓扑涡旋可产生介观磁化结构。
英文摘要：
We calculated the structural, electronic and magnetic properties of FeSe within density-functional theory at the generalized gradient approximation level. First, we studied how the bandwidth of the d-bands at the Fermi energy are renormalized by adding simple corrections: Hubbard U, Hunds J and by introducing long-range magnetic orders. We found that introducing either a striped or a staggered dimer antiferromagnetic order brings the bandwidths -- which are starkly overestimated at the generalized gradient approximation level -- closer to those experimentally observed. Second, for the ferromagnetic, the striped, checkerboard and the staggered dimer antiferromagnetic order, we investigate the change in magnetic formation energy with local magnetic moment of Fe at a pressure up to 6 GPa. The bilinear and biquadratic exchange energies are derived from the Heisenberg model and noncollinear first-principles calculations, respectively. We found a non-trivial behavior of the spin-exchange parameters on the magnetization, and we put forward a field-theory model that rationalizes these results in terms of two-dimensional spin and orbital fluctuations. The character of these fluctuations can be either that of a standard density wave or a topological vortex. Topological vortexes can result in mesoscopic magnetization structures.
机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。
