CAREER: Study of Emergent Ground States and Bosonic Excitations in Materials with Strong Spin-Lattice Coupling

职业：强自旋晶格耦合材料中的新兴基态和玻色子激发的研究

• 批准号: 1455264
• 负责人: Gregory MacDougall
• 金额: $ 61.26万
• 依托单位: University of Illinois at Urbana-Champaign
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2015
• 资助国家: 美国
• 起止时间: 2015-09-01 至 2021-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1455264&HistoricalAwards=false
• 关键词: CAREER; Study; Emergent; Ground; States

*Non-technical Abstract*Our current understanding of materials is that they are a rigid lattice of atomic nuclei, which can vibrate, but largely serve as an impartial backdrop for the motion and spinning of charged electrons. In materials where the vibrations of nuclei strongly interact with the electron spins, a number of novel behaviors have been recently reported, which are poorly understood but potentially useful for future electronic devices and energy technologies. The current project seeks to understand these behaviors through the identification of key model systems in which the effects of strong spin-lattice coupling are prominent and can be studied without additional complicating factors. Powders and large single crystals of novel materials are being prepared using equipment and expertise at the University of Illinois, and atomic motion and magnetic properties are subsequently being studied using cutting edge facilities at national laboratories. The research team is focusing specifically on behaviors deemed most promising from preliminary explorations. This work is pertinent to the understanding and control of common material properties and will help further the development of a number of new technologies. A major theme of this project is also to drive new states of matter, which might have untold useful or interesting properties. These activities provide an ideal environment for the training of graduate and undergraduate students in the methods of materials production and characterization, which is in line with current national priorities. The principal investigator is also developing a graduate course on experimental methods for studying materials at the University of Illinois, to provide greater understanding for the next generation of scientists of research opportunities open to them and to foster collaboration among student researchers. Through a series of public lectures and online exchanges, the principal investigator is also helping to educate the general populace about the science of materials, magnetism and modern experimental probes of matter.*Technical Abstract*This project seeks to identify, characterize and control the magnetic properties of materials containing a strong coupling between lattice and spin degrees-of-freedom. A joint materials development and experimental program is being pursued, where specific materials strategies will be employed to synthesize model spin-lattice coupled systems and to grow crystals, and subsequently to study them via neutron scattering and muon spin rotation using facilities at national laboratories. To maximize impact, the proposal focuses on four specific areas deemed promising from preliminary work. These include driving transitions to novel magnetic ground states with field, doping or pressure; investigating phase separation and long length-scale ordering of domains in materials; exploring how spin-lattice coupling modifies collective excitations; and creating new superconductors having strong coupling between spin and orbit angular momentum. Spin-lattice coupling effects are relevant to the discussion of a wide range of physics topics, including colossal response functions, multiferroism, superconductivity, and thermal conductivity. The current work will further discussion of these phenomena through the identification and development of model materials, where spin-lattice coupling effects can be isolated, controlled and studied directly. By studying spin-lattice coupling effects in isolation, this work will clarify the discussion and understanding of its role in more complex material systems.

* 非技术摘要 * 我们目前对材料的理解是，它们是原子核的刚性晶格，可以振动，但在很大程度上作为带电电子运动和旋转的公正背景。在原子核的振动与电子自旋强烈相互作用的材料中，最近报道了许多新的行为，这些行为知之甚少，但对未来的电子器件和能源技术可能有用。目前的项目试图通过识别关键模型系统来理解这些行为，在这些模型系统中，强自旋-晶格耦合的影响 是突出的，可以在没有额外复杂因素的情况下进行研究。正在利用伊利诺斯大学的设备和专门知识制备新材料的粉末和大单晶，随后利用国家实验室的尖端设施研究原子运动和磁性。研究小组特别关注初步探索中被认为最有前途的行为。这项工作与理解和控制常见的材料特性有关，并将有助于进一步开发一些新技术。这个项目的一个主要主题也是推动新的物质状态，这可能有数不清的有用或有趣的属性。这些活动为研究生和本科生提供了材料生产和表征方法培训的理想环境，这符合当前的国家优先事项。首席研究员还在伊利诺伊大学开设一门关于材料研究实验方法的研究生课程，以使下一代科学家更好地了解向他们开放的研究机会，并促进学生研究人员之间的合作。通过一系列的公开讲座和在线交流，首席研究员还帮助教育普通民众关于材料科学，磁学和现代物质实验探针。技术摘要 * 该项目旨在识别、表征和控制包含晶格和自旋自由度之间强耦合的材料的磁性。正在进行一项联合材料开发和实验计划，其中将采用特定的材料战略来合成模型自旋-晶格耦合系统并生长晶体，随后使用国家实验室的设施通过中子散射和μ子自旋旋转对其进行研究。为了最大限度地扩大影响，该提案侧重于初步工作认为有希望的四个具体领域。这些包括驱动转换到新的磁基态与场，掺杂或压力;调查相分离和长尺度有序的域在材料中;探索自旋晶格耦合如何修改集体激发;并创建新的超导体之间的自旋和轨道角动量强耦合。自旋-晶格耦合效应与广泛的物理学主题的讨论有关，包括巨大的响应函数，多重铁性，超导性和热导率。目前的工作将进一步讨论这些现象，通过识别和发展的模型材料，自旋-晶格耦合效应可以被隔离，控制和直接研究。通过孤立地研究自旋-晶格耦合效应，这项工作将澄清对它在更复杂的材料系统中作用的讨论和理解。