Strongly correlated electron systems studied by strain-dependent angle-resolved photoemission spectroscopy

通过应变相关角分辨光电子能谱研究强相关电子系统

• 批准号: 414152718
• 负责人: Dr. Heike Pfau
• 金额: --
• 依托单位: National Accelerator Laboratory SLAC
• 依托单位国家: 德国
• 项目类别: Research Fellowships
• 财政年份: 2018
• 资助国家: 德国
• 起止时间: 2017-12-31 至 2020-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/414152718?language=en
• 关键词: Strongly; correlated; electron; systems; studied

The foundation of all modern technology is the power of quantum theories to predict mechanical, optical and electrical properties with high precision. Common metals and semiconductors like copper or silicon are well described by band theories. In contrast, understanding the interactions that lead to the remarkable properties of strongly correlated electron materials such as high-temperature superconductivity remains deeply challenging. The coupling of spin, orbital and lattice degrees of freedom in strongly correlated electron systems leads to complex phase diagrams with intertwined or competing orders. Understanding such phase diagrams is essential for formulating effective quantum theories.Angle-resolved photoemission spectroscopy (ARPES) has contributed profoundly to our understanding of correlated materials by accessing the electronic band structure directly. However, ARPES is incompatible with common non-thermal tuning parameters like magnetic fields, electric fields, or pressure. Since these tuning parameters build-up phase diagrams, the microscopic information from ARPES is often missing.My goal is to combine anisotropic strain as a quantitative, non-thermal tuning parameter with ARPES and add electronic structure information to the phase diagram of quantum materials. I have developed a prototype of a strain apparatus for APRES and performed first successful tests. My proposal aims at employing this new technique to study iron-based superconductors and strontium ruthenate. Their thermodynamic and transport properties can be tuned by anisotropic strain, which makes them prime candidates. The nematic susceptibility in iron-based superconductors derived from strain-dependent ARPES will substantially contribute to identify the driving order parameter of the nematic phase, its interplay with superconductivity and possible quantum critical behavior. Strontium ruthenate is one of the few materials discussed in terms of odd-parity superconductivity and I will be able to shed light on its superconducting order parameter. These studies will considerably improve our understanding of the phase diagrams of these two materials. They will also feedback to the improvement of the current strain apparatus and establish it as a well characterized tuning device for ARPES in strongly correlated materials.

所有现代技术的基础是量子理论的力量，以高精度预测机械，光学和电学特性。常见的金属和半导体，如铜或硅，可以用能带理论很好地描述。相比之下，理解导致强相关电子材料（如高温超导性）显着特性的相互作用仍然具有很大的挑战性。在强关联电子系统中，自旋、轨道和晶格自由度的耦合导致了具有相互缠绕或竞争顺序的复杂相图。角分辨光电子能谱（ARPES）通过直接测量电子能带结构，为我们理解相关材料做出了重要贡献。然而，ARPES与常见的非热调谐参数（如磁场、电场或压力）不兼容。由于这些调谐参数构建了相图，所以ARPES中的微观信息常常丢失，我的目标是将各向异性应变作为定量的非热调谐参数与ARPES结合起来，并将电子结构信息添加到量子材料的相图中。我已经为APRES开发了一个应变仪的原型，并进行了首次成功的测试。我的提案旨在利用这种新技术来研究铁基超导体和钌酸锶。它们的热力学和输运性质可以通过各向异性应变来调节，这使它们成为主要的候选者。铁基超导体的超导磁化率来自应变相关的ARPES将大大有助于确定的驱动序参数的超导相，其与超导性和可能的量子临界行为的相互作用。锶是讨论奇宇称超导性的少数材料之一，我将能够阐明其超导序参量。这些研究将大大提高我们对这两种材料的相图的理解。他们还将反馈到改进的电流应变仪，并建立它作为一个很好的表征调谐装置的ARPES在强相关材料。

项目成果

Low work function in the 122-family of iron-based superconductors

• DOI: 10.1103/physrevmaterials.4.034801
• 发表时间: 2020-02
• 期刊: Physical Review Materials
• 影响因子: 3.4
• 作者: H. Pfau;H. Pfau;H. Soifer;H. Soifer;J. Sobota;J. Sobota;A. Gauthier;A. Gauthier;C. Rotundu;J. C. Palmstrom;J. C. Palmstrom;I. Fisher;I. Fisher;G. Chen;H. Wen;Zhixuan Shen;Z. Shen;Zhixuan Shen;P. Kirchmann

Tuning time and energy resolution in time-resolved photoemission spectroscopy with nonlinear crystals

• DOI: 10.1063/5.0018834
• 发表时间: 2020-09-07
• 期刊: JOURNAL OF APPLIED PHYSICS
• 影响因子: 3.2
• 作者: Gauthier, Alexandre;Sobota, Jonathan A.;Kirchmann, Patrick S.
• 通讯作者: Kirchmann, Patrick S.

Nematic Energy Scale and the Missing Electron Pocket in FeSe

向列相能量尺度和 FeSe 中缺失的电子袋

• DOI: 10.1103/physrevx.9.041049
• 发表时间: 2019-12-06
• 期刊: PHYSICAL REVIEW X
• 影响因子: 12.5
• 作者: Yi, M.;Pfau, H.;Birgeneau, R. J.
• 通讯作者: Birgeneau, R. J.