MuSR and multi-probe studies of spin-charge interplays in emergent quantum phenomena

涌现量子现象中自旋电荷相互作用的 MuSR 和多探针研究

• 批准号: 2104661
• 负责人: Yasutomo Uemura
• 金额: $ 48.51万
• 依托单位: Columbia University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2023
• 资助国家: 美国
• 起止时间: 2023-03-15 至 2026-02-28
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2104661&HistoricalAwards=false
• 关键词: MuSR; multi; probe; studies; spin

Non-technical abstract: Superconductivity is a prominent macroscopic manifestation of quantum phenomena, which can be applied to quantum computing devices, loss-free power-transmission, high-field magnets and high-speed trains. Superconducting mechanism for simple metals, such as Sn and Al, was explained by the theory of Bardeen, Cooper and Schrieffer (BCS) in 1957. However, since the discovery of cupper-oxide systems in 1986, many "unconventional" superconductors (USC) were found to exhibit signatures unexpected in BCS theory. Many of them are in the proximity to materials showing Mott metal-insulator transitions (MIT). Strong interplay between electric (charge) and magnetic (spin) interactions seems to be crucial for the USC and MIT phenomena. By performing muon spin relaxation, neutron scattering and scanning-tunneling microscopy measurements on selected systems, and by interpreting the results using Uemura-plot phenomenology developed by the PI since 1989, the present project aims to elucidate charge-spin interplays and unveil essential mechanisms of USC and MIT. The project also aims to clarify the role of dimensionality and topology on phase transitions of these systems and selected novel magnetic systems. Involving students and young researchers, these projects help develop human resources in international collaborations at major accelerator-based facilities. Technical abstract:Emergent quantum materials, such as unconventional superconductor (SC), Mott transition, Skyrmion and topological systems, exhibit novel quantum phenomena based on intertwining interplays of spin, charge, geometry and topology. Muon spin relaxation (MuSR) is a strong probe for studying these systems, with unique sensitivity to superfluid density in SC's and dynamic spin fluctuations, static order parameter, volume fraction and local spin correlations in magnetic transitions. By performing MuSR studies in combination with complementary measurements by neutron scattering and Scanning Tunneling Microscopy (STM), the PI aims to test and clarify: (1) a hypothesis of highly entangled spin-charge gap, analogous to the magnetic resonance mode, existing in non-superconducting Mott transition systems Ba(Co,Ni)S2 and Ni(S,Se)2; (2) magnetic-field-induced change in the normal state of Hg1201 high-Tc cuprates; (3) effect of topology in dynamic critical behavior of MnSi and other Skyrimon systems; and (4) spin fluctuations in topological Weyl semimetal Co3(Sn,In)2S2 with Kagome lattice. The PI also integrate these experimental efforts with his phenomenology on unconventional SC's towards the ultimate goal to advance comprehensive understandings of unconventional superconductivity. In addition, Frontiers of Condensed Matter Physics (FCMP) lectures and associated workshops organized by the PI facilitate motivated graduate students / researchers from over the world to study forefront CMP researches on superconductivity and magnetism with leading contributors.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.

非技术摘要：超导是量子现象的一种突出的宏观表现，可应用于量子计算设备、无损耗电力传输、高场磁体和高速列车。 1957 年，Bardeen、Cooper 和 Schrieffer (BCS) 的理论解释了锡和铝等简单金属的超导机制。然而，自从 1986 年发现氧化铜系统以来，许多“非常规”超导体 (USC)被发现表现出 BCS 理论中意想不到的特征。 其中许多都接近显示莫特金属-绝缘体转变（MIT）的材料。 电（电荷）和磁（自旋）相互作用之间的强烈相互作用似乎对于南加州大学和麻省理工学院的现象至关重要。 通过对选定的系统进行 μ 子自旋弛豫、中子散射和扫描隧道显微镜测量，并使用 PI 自 1989 年以来开发的 Uemura-plot 现象学解释结果，本项目旨在阐明电荷自旋相互作用并揭示电荷自旋相互作用的基本机制。南加州大学和麻省理工学院。 该项目还旨在阐明维度和拓扑对这些系统和选定的新型磁系统的相变的作用。这些项目涉及学生和年轻研究人员，有助于在主要加速器设施的国际合作中培养人力资源。 技术摘要：新兴的量子材料，例如非常规超导体（SC）、莫特跃迁、斯格明子和拓扑系统，表现出基于自旋、电荷、几何和拓扑相互作用的新颖量子现象。 μ 子自旋弛豫 (MuSR) 是研究这些系统的强大探针，对 SC 中的超流体密度以及磁跃迁中的动态自旋涨落、静态序参数、体积分数和局部自旋相关性具有独特的敏感性。通过结合中子散射和扫描隧道显微镜 (STM) 的补充测量进行 MuSR 研究，PI 旨在测试和澄清：(1) 高度纠缠的自旋电荷间隙的假设，类似于磁共振模式，存在于非超导莫特过渡系Ba(Co,Ni)S2和Ni(S,Se)2； (2) Hg1201高Tc铜酸盐正常状态下磁场引起的变化； (3)拓扑对MnSi和其他Skyrimon系统动态临界行为的影响； (4)具有Kagome晶格的拓扑Weyl半金属Co3(Sn,In)2S2的自旋涨落。 PI 还将这些实验工作与他对非常规超导现象学的研究相结合，以实现促进对非常规超导性的全面理解的最终目标。 此外，由 PI 组织的凝聚态物理前沿 (FCMP) 讲座和相关研讨会有助于来自世界各地的研究生/研究人员与主要贡献者一起研究超导性和磁性的前沿 CMP 研究。该奖项反映了 NSF 的法定使命，并具有通过使用基金会的智力优点和更广泛的影响审查标准进行评估，被认为值得支持。

项目成果

Energy-scale considerations of unconventional superconductors—implications to condensation and pairing

非常规超导体的能量尺度考虑——对凝聚和配对的影响

• DOI: 10.1016/j.physc.2023.1354361
• 发表时间: 2023-11
• 期刊: Physica C: Superconductivity and its Applications
• 作者: Uemura; Yasutomo J.
• 通讯作者: Yasutomo J.

Two superconducting states with broken time-reversal symmetry in FeSe 1−x S x

FeSe 1–x S x 中时间反转对称性破缺的两种超导态

• DOI: 10.1073/pnas.2208276120
• 发表时间: 2023-05-23
• 期刊: Proceedings of the National Academy of Sciences
• 作者: Matsuura, Kohei;Roppongi, Masaki;Qiu, Mingwei;Sheng, Qi;Cai, Yipeng;Yamakawa, Kohtaro;Guguchia, Zurab;Day, Ryan P.;Kojima, Kenji M.;Damascelli, Andrea;et al
• 通讯作者: et al