Collaborative Research: DMREF: Discovery of novel magnetic materials through pseudospin control

非技术描述：材料发现需要新的工具来实现设计原则。许多与技术相关的材料的性质，如超导体的完美导电性和磁体的电流控制，都源于电子的自旋。 该项目将使用赝自旋（类似于电子自旋的量子力学自由度）作为材料发现的新工具。 该研究将遵循协作和迭代的闭环材料基因组计划方法，结合分析和预测计算理论，同时一次一个原子层的材料外延生长，并使用先进的显微镜和光谱技术进行表征。该项目将开发基于控制材料设计中的赝自旋的新指导原则，这是量子材料发现的范式转变，将使超导体能够维持高磁场和新型磁体。这项活动将为下一代量子劳动力提供培训。技术说明：该项目旨在开发赝自旋控制作为发现新磁态和超导性的材料设计工具。赝自旋的概念来源于布洛赫电子在时间反转和反转对称下的双重Kramers简并。通常情况下，赝自旋在旋转下表现为自旋-1/2，推动了我们对超导体中的库珀配对、斯通纳铁磁性和塞曼场控制自旋的理解。然而，对于具有非对称空间群对称性的晶体，赝自旋可以表现得与正常自旋-1/2非常不同。这可以导致新的磁状态，包括交流磁体和奇宇称多极磁体，并定性地改变超导对磁场的响应。这个项目将初步发展一个新的和全面的理论，这种新的赝自旋。然后，密度泛函计算将用于指导寻找由非自旋1/2赝自旋驱动的具有理想性质的材料，包括高场超导体和新型磁体。候选材料的薄膜将通过分子束外延在各种钙钛矿氧化物衬底上生长，这些钙钛矿氧化物衬底通过定制晶格应变、邻近效应、电荷掺杂以及电和光选通来提供磁性和超导性质的可调谐性。例如，交流磁体中的晶体霍尔效应和奇宇称磁体中的非线性霍尔效应的实验演示将提供验证理论预测的手段和合成新磁相的途径。该奖项反映了NSF的法定使命，并通过使用基金会的智力价值和更广泛的影响审查标准进行评估，被认为值得支持。

Non-technical Description: Materials discovery requires new tools that enable design principles. The properties of many technologically relevant materials, such as perfect conductivity in superconductors and electric current control of magnets, arise from the spin of electrons. This project will use pseudospin - a quantum mechanical degree of freedom analogous to electron spin - as a new tool for materials discovery. The research will follow the collaborative and iterative closed-loop Materials Genome Initiative approach by combining analytic and predictive computational theory, together with epitaxial growth of materials one atomic layer at a time, and characterization using advanced microscopy and spectroscopy techniques. This project will develop new guiding principles based on controlling pseudospin in materials design, a paradigm shift in quantum materials discovery that will enable both superconductors that can sustain high magnetic fields and novel magnets. This activity will provide training for the next-generation quantum workforce. Technical Description: This project aims to develop pseudospin control as a materials design tool for discovering new magnetic states and superconductivity. The concept of pseudospin derives from the two-fold Kramers degeneracy of Bloch electrons when time-reversal and inversion symmetries are present. Normally, pseudospin behaves as spin-1/2 under rotations, driving much of our understanding of Cooper pairing in superconductors, Stoner ferromagnetism, and spin control by Zeeman fields. However, for crystals with non-symmorphic space group symmetry, pseudospin can behave very differently than normal spin-1/2. This can lead to novel magnetic states, including altermagnets and odd-parity multipole magnets, and qualitatively alter the superconducting response to magnetic fields. This project will initially develop a new and comprehensive theory of this novel pseudospin. Then density functional calculations will be used to guide the search for materials with desirable properties driven by non-spin-1/2 pseudospin, including high-field superconductors and novel magnets. Thin films of candidate materials will be grown by molecular beam epitaxy on various perovskite oxide substrates, which offer tunability of magnetic and superconducting properties by tailoring lattice strain, proximity effects, charge doping, and electric and optical gating. The experimental demonstration of, for example, crystal Hall effects in altermagnets and the nonlinear Hall effect in odd-parity magnets will provide both a means to validate the theoretical predictions and a path to synthesize new magnetic phases.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.