Unconventional metals in carrier-tuned spin-orbit Mott materials

载流子调谐自旋轨道莫特材料中的非常规金属

• 批准号: 1905801
• 负责人: Stephen Wilson
• 金额: $ 50.18万
• 依托单位: University of California-Santa Barbara
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2019
• 资助国家: 美国
• 起止时间: 2019-08-15 至 2023-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1905801&HistoricalAwards=false
• 关键词: Unconventional; metals; carrier; tuned; spin

Nontechnical Abstract: This project explores the fascinating and complex electronic behaviors endemic to a class of metals born from insulators with both strong interactions between electrons and strong coupling between the electron's orbital motion and its inherent magnetic moment or spin. These 'spin-orbit assisted Mott insulators' can be turned into metals by adding charge carriers, where many exciting states such as high temperature superconductivity and electronic states for quantum information are predicted. Ultrahigh purity crystals of these metals are grown in the project and experiments exploring the structural, magnetic, and electronic properties of their unusual metallic states performed. In particular, research activities target a series of doped iridium oxide materials whose parent insulating states have recently been shown to collapse into metals with anomalous charge and spin properties. This builds the knowledgebase needed for assessing the viability of these materials for potential future superconducting and quantum information applications. The project trains graduate students in advanced crystal growth techniques as well as in advanced scattering techniques at national user facilities, addressing the national need for trained personnel in both arenas. Additionally, the project executes a multitier education and outreach effort targeted at promoting diverse participation in STEM disciplines and within materials science in particular. This is achieved through undergraduate research opportunities targeted at attracting and retaining underrepresented demographics within materials science.Technical Abstract: This project experimentally explores two classes of iridium oxides where canonical spin-orbit Mott states appear--the Ruddlesden-Popper series of Srn+1IrnO3n+1 and the rare-earth series of pyrochlore Al2Ir2O7. Key variants of these compounds are explored with the goals of understanding the origins of unconventional spin and charge density wave formation in the Ruddlesden-Popper iridates, their relation to strange-metal behavior and potential superconductivity in these systems, and the coupling between magnetism and the metal-insulator transitions of the pyrochlore iridates. All of these phenomena are of considerable interest for identifying exotic electronic states predicted to manifest in these materials, with examples ranging from high-temperature superconductivity to magnetic Weyl semimetal states. Experimental approaches include synchrotron x-ray and neutron scattering measurements, bulk electronic properties (such as charge transport and magnetization) measurements, and complementary electronic probes performed via a network of collaborators. A key enabling tool in the research is the use high-pressure floating zone crystal growth techniques to create ultrahigh purity specimens for study. By leveraging this tool, the project creates new pathways for discovering predicted and other unforeseen unconventional electronic states in carrier-doped spin-orbit assisted Mott materials.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：该项目探索了一类由绝缘体产生的金属特有的迷人而复杂的电子行为，这些绝缘体具有电子之间的强相互作用以及电子轨道运动与其固有磁矩或自旋之间的强耦合。 这些“自旋轨道辅助的莫特绝缘体”可以通过添加电荷载流子变成金属，其中许多激发态，如高温超导性和量子信息的电子态被预测。 这些金属的超高纯度晶体在该项目中生长，并进行了探索其不寻常金属状态的结构，磁性和电子特性的实验。 特别是，研究活动的目标是一系列掺杂的氧化铱材料，其母体绝缘状态最近已被证明崩溃成具有异常电荷和自旋特性的金属。这建立了评估这些材料未来潜在的超导和量子信息应用的可行性所需的知识库。该项目在国家用户设施培训研究生掌握先进的晶体生长技术和先进的散射技术，以满足国家在这两个领域对训练有素人员的需求。 此外，该项目还开展了多层次的教育和外联工作，旨在促进STEM学科，特别是材料科学的多元化参与。 这是通过本科生的研究机会，有针对性地吸引和保留人口不足的材料science.Technical摘要：该项目实验探讨了两类典型的自旋轨道莫特状态出现的铱氧化物-Ruddlesden-Popper系列Srn+1 IrnO 3 n +1和稀土系列烧绿石Al 2 Ir 2 O 7。 这些化合物的关键变体进行了探索，目的是了解Ruddlesden-Popper虹彩酸盐中非常规自旋和电荷密度波形成的起源，它们与这些系统中的奇异金属行为和潜在超导性的关系，以及磁性与烧绿石虹彩酸盐的金属-绝缘体转变之间的耦合。 所有这些现象对于识别预测在这些材料中表现的奇异电子状态都具有相当大的兴趣，例如从高温超导性到磁性Weyl半金属状态。 实验方法包括同步加速器X射线和中子散射测量，体电子特性（如电荷传输和磁化）测量，以及通过合作者网络进行的互补电子探针。 研究中的一个关键使能工具是使用高压浮区晶体生长技术来创建用于研究的高纯度样品。 通过利用这一工具，该项目为发现载流子掺杂自旋轨道辅助Mott材料中的预测和其他不可预见的非常规电子状态创造了新的途径。该奖项反映了NSF的法定使命，并通过使用基金会的知识价值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

Monopole-limited nucleation of magnetism in Eu2Ir2O7

• DOI: 10.1103/physrevb.101.174435
• 发表时间: 2020-03
• 期刊: Physical Review B
• 影响因子: 3.7
• 作者: G. Prando;Prachi Telang;Stephen D. Wilson;M. Graf;Surjeet Singh

Atomic-scale fragmentation and collapse of antiferromagnetic order in a doped Mott insulator

掺杂莫特绝缘体中反铁磁序的原子尺度碎裂和崩溃

• DOI: 10.1038/s41567-019-0671-9
• 发表时间: 2019
• 期刊: Nature Physics
• 影响因子: 19.6
• 作者: Zhao, He;Manna, Sujit;Porter, Zach;Chen, Xiang;Uzdejczyk, Andrew;Moodera, Jagadeesh;Wang, Ziqiang;Wilson, Stephen D.;Zeljkovic, Ilija
• 通讯作者: Zeljkovic, Ilija

Nonsymmorphic Dirac semimetal and carrier dynamics in the doped spin-orbit-coupled Mott insulator Sr2IrO4

• DOI: 10.1103/physrevb.102.041108
• 发表时间: 2020-06
• 期刊: Physical Review B
• 影响因子: 3.7
• 作者: Han Jeong Woo;Sun-Woo Kim;W. Kyung;W. Kyung;Chung-Jong Kim;G. Cao;Xiao Chen;S. Wilson

Electronic nature of the pseudogap in electron-doped Sr2IrO4

电子掺杂 Sr2IrO4 中赝能隙的电子性质

• DOI: 10.1038/s41535-022-00467-1
• 发表时间: 2022
• 期刊: npj Quantum Materials
• 影响因子: 5.7
• 作者: Peng, Shuting;Lane, Christopher;Hu, Yong;Guo, Mingyao;Chen, Xiang;Sun, Zeliang;Hashimoto, Makoto;Lu, Donghui;Shen, Zhi-Xun;Wu, Tao
• 通讯作者: Wu, Tao

Spectroscopic Evidence for Electron-Boson Coupling in Electron-Doped Sr2IrO4

• DOI: 10.1103/physrevlett.123.216402
• 发表时间: 2019-11-21
• 期刊: PHYSICAL REVIEW LETTERS
• 影响因子: 8.6
• 作者: Hu, Yong;Chen, Xiang;He, J. -F.
• 通讯作者: He, J. -F.