ARPES Studies of CMR Oxides and Related Materials

CMR 氧化物及相关材料的 ARPES 研究

• 批准号: 1007014
• 负责人: Daniel Dessau
• 金额: $ 37.5万
• 依托单位: University of Colorado at Boulder
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2010
• 资助国家: 美国
• 起止时间: 2010-09-01 至 2014-02-28
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1007014&HistoricalAwards=false
• 关键词: ARPES; Studies; CMR; Oxides; Related

****NON-TECHNICAL ABSTRACT****The colossal magnetoresistive (CMR) oxides are an important set of electronic materials, which present an extreme or colossal change in their electrical resistance upon the application of a magnetic field (hence the term colossal magnetoresistance). These materials have potential for applications - for example as sensors in next-generation magnetic storage devices. However, much of the physics behind CMR and other related effects in these materials is not yet understood. The goal of this project is to advance the understanding of these and related materials using the technique of photoemission spectroscopy - the principles of which were explained by Einstein in his Nobel-winning 1905 paper. The photoemission experiments will be performed with ultraviolet lasers and with synchrotron radiation sources such as the Advanced Light Source, Berkeley Labs, California. Experiments will be performed over a wider parameter range than has been done previously, which is expected to provide much deeper insights into the causes of the behavior of these materials. The inclusion of students (including undergraduates) in this research program is important, as it will provide them with useful skills for future careers in academia, national laboratories, or industry. Providing undergraduates with meaningful research experiences is considered one of the most effective ways to attract talented students and to retain them in careers in science and engineering. ****TECHNICAL ABSTRACT****High resolution angle resolved photoemission (ARPES) will be used to study the electronic structure of colossal magnetoresistive (CMR) oxides and other related materials. An emphasis will be placed on cleaved single crystals of the bilayer manganites, which give the best window into the intrinsic low energy electronic excitations of this general class of materials. Experiments will be performed over a wide parameter range of doping and temperature so as to access and eventually understand the complex and rich evolution of the phase diagram. Effects that are important in this phase diagram are the evolution of ferromagnetism, antiferromagnetism, canted magnetism, and paramagnetism, metals, insulators, charge and orbital order and disorder. Electronic gaps and pseudogaps from this order as well as from electron-phonon coupling and localization effects also are relevant. The cooperation and competition between these many effects is ultimately responsible for the "colossal" responses of the systems to minor changes in their external parameters. The goal therefore is to understand the detailed electronic structure, magnetic structure, and interactions in these various phases, as well as to understand how these phases cooperate or compete with each other. The inclusion of students (including undergraduates) in this research program is important, as it will provide them with useful skills for future careers in academia, national laboratories, or industry. Providing undergraduates with meaningful research experiences is considered one of the most effective ways to attract talented students and to retain them in careers in science and engineering.

****非技术摘要****巨大的磁化（CMR）氧化物是一组重要的电子材料，在应用磁场时，其电阻的极端或巨大变化（因此，术语巨大的磁磁性）。 这些材料具有应用的潜力 - 例如，在下一代磁性存储设备中作为传感器。 但是，CMR背后的许多物理和这些材料中其他相关效果尚不清楚。 该项目的目的是使用光发射光谱技术提高对这些和相关材料的理解 - 爱因斯坦在他的诺贝尔奖的1905年论文中解释了其原理。 光发射实验将使用紫外线激光器和同步辐射源进行，例如高级光源，加利福尼亚州伯克利实验室。 实验将在更广泛的参数范围内进行，而不是以前进行，这预计将为这些材料行为的原因提供更深入的见解。 该研究计划中包括学生（包括本科生）的学生很重要，因为它将为他们提供学术界，国家实验室或行业的未来职业的有用技能。 为大学生提供有意义的研究经验被认为是吸引才华横溢的学生并将其保留在科学和工程学领域的最有效方法之一。 ****技术摘要****高分辨率角度分辨光发射（ARPE）将用于研究巨大磁磁性（CMR）氧化物和其他相关材料的电子结构。 将重点放在双层锰矿的切割单晶上，这使最佳的窗口融入了这种一般材料类别的内在低能电子激发。 实验将在掺杂和温度的广泛参数范围内进行，以便访问并最终了解相图的复杂而丰富的演化。 在此阶段图中很重要的效果是铁磁，抗铁磁，磁磁性和顺磁性，金属，绝缘子，电荷和轨道秩序和轨道秩序和混乱的演变。 该顺序的电子间隙和伪库以及电子 - 音波耦合和定位效应也很重要。 这些许多效果之间的合作与竞争最终是对系统对其外部参数的微小变化的“巨大”响应的原因。 因此，目标是了解这些各个阶段中的详细电子结构，磁性结构和相互作用，并了解这些阶段如何相互合作或竞争。 该研究计划中包括学生（包括本科生）的学生很重要，因为它将为他们提供学术界，国家实验室或行业的未来职业的有用技能。 为大学生提供有意义的研究经验被认为是吸引才华横溢的学生并将其保留在科学和工程学领域的最有效方法之一。