Ab initio modelling of structural and magnetic phase transitions under pressure and doping for the iron based superconductors

铁基超导体在压力和掺杂下的结构和磁相变的从头建模

• 批准号: 168398348
• 负责人: Professorin Dr. Maria Roser Valenti
• 金额: --
• 依托单位: Institut für Theoretische Physik
• 依托单位国家: 德国
• 项目类别: Priority Programmes
• 财政年份: 2010
• 资助国家: 德国
• 起止时间: 2009-12-31 至 2019-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/168398348?language=en
• 关键词: Ab; initio; modelling; structural; magnetic

The goal of this project is a better understanding of the interplay between magnetism, structural transitions and superconductivity as a function of pressure and doping in the iron-based superconductors by a combination of ab initio density functional theory (DFT) calculations, Car- Parrinello molecular dynamics and dynamical mean field theory (DMFT). We will explore the nature of the structural, magnetic and superconducting phase transitions in these multiband systems i) by performing electronic structure calculations in the framework of first principles (Car- Parrinello) molecular dynamics. We will compare bandstructures with ARPES results. ii) by performing momentum-dependent and orbital-resolved susceptibility calculations at various pressures and dopings. For the latter we will implement the evaluation of the corresponding matrix elements within DFT. These calculations will allow us to quantify the amount of intra- and inter-band as well as intra- and inter-orbital nesting, which may be a key quantity for understanding the interplay between magnetism and superconductivity. iii) by performing a systematic investigation of the optical properties as a function of pressure and doping within DFT and DMFT. The possible correlated nature of these materials will be analyzed. iv) by calculating angle dependent de Haas-van Alphen (dHvA) frequencies and compare them to available measurements. These calculations will allow a better characterization of the evolution of Fermi surfaces under pressure and doping. v) by analyzing the spin dynamics in these systems under pressure in terms of susceptibility calculations as well as non-collinear calculations. In the iron chalcogenide (“11”) compounds, a non-collinear magnetic ground state was observed, which needs to be addressed by corresponding calculations. And finally we plan to search for adequate exchange-correlation functionals within DFT that allow a better prediction of structures and magnetic properties.

该项目的目标是通过从头计算密度泛函理论（DFT）计算，Car- Parrinello分子动力学和动态平均场理论（DMFT）的组合，更好地理解铁基超导体中作为压力和掺杂函数的磁性，结构转变和超导性之间的相互作用。我们将探索这些多带系统中的结构，磁性和超导相变的性质i）通过在第一原理（Car- Parrinello）分子动力学框架中进行电子结构计算。我们将比较能带结构与ARPES结果。ii）通过在各种压力和掺杂下进行动量相关和轨道分辨的磁化率计算。对于后者，我们将在DFT中实现相应矩阵元素的求值。这些计算将使我们能够量化带内和带间以及轨道内和轨道间嵌套的数量，这可能是理解磁性和超导性之间相互作用的关键量。iii）通过在DFT和DMFT内执行作为压力和掺杂的函数的光学性质的系统研究。将分析这些材料的可能相关性质。iv）通过计算角度相关的de Haas-van Alphen（dHvA）频率并将它们与可用的测量值进行比较。这些计算将允许压力和掺杂下的费米表面的演变更好的表征。v）通过磁化率计算以及非共线计算分析这些系统在压力下的自旋动力学。在铁硫族化合物（“11”）中，观察到非共线的磁性基态，这需要通过相应的计算来解决。最后，我们计划在DFT中寻找足够的交换相关泛函，以便更好地预测结构和磁性。