CAREER: Low-Dimensional Spin Systems: Interplay of Chemical Pressure on Triangular Lattices with Spin- and Orbital Degrees of Freedom

职业：低维自旋系统：三角形晶格上化学压力与自旋和轨道自由度的相互作用

• 批准号: 1149899
• 负责人: Angela Moeller
• 金额: $ 47.31万
• 依托单位: University of Houston
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2012
• 资助国家: 美国
• 起止时间: 2012-01-15 至 2016-12-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1149899&HistoricalAwards=false
• 关键词: CAREER; Low; Dimensional; Spin; Systems

TECHNICAL SUMMARY:The objective of this CAREER proposal, supported by the Solid State and Materials Chemistry (SSMC) program, is to understand the effects of chemical pressure on geometrically frustrated lattices in the presence of spin and orbital degrees of freedom. A recently identified and subsequently synthesized new series of compounds exhibiting a triangular lattice of magnetic ions confined in a robust two-dimensional building block has emerged as a suitable template to investigate: (1) the impact of induced slight structural distortions and (2) the dependence of the magnetic correlations on the respective spin system. A unique opportunity to derive insights into tuning ferromagnetic and anti-ferromagnetic correlations mediated through super-exchange pathways has emerged for this series of compounds. The investigations are mainly experimental and encompass solid state chemistry synthesis, spectroscopy, magnetization, and specific heat measurements. The scientific impact of this work will contribute to a fundamental understanding of phenomena occurring on geometrically frustrated systems, including aspects of spin-orbit coupling for divalent and trivalent 3d transition metal cations. Furthermore, the discovery of new members of the highly unique class of ferromagnetic insulators represents an additional exciting advance and an important contribution to the field of multifunctional materials. NON-TECHNICAL SUMMARY:Advances in the field of next-generation materials with relevance to energy and sensors rely on the development of a fundamental understanding of the properties of materials. Further, the design of new classes of materials and the ability to control important functional parameters of these materials require a detailed understanding of the mechanisms at work. To this end, the conceptual framework underlying the proposed research activities, supported by the Solid State and Materials Chemistry program (SSMC), seeks to establish the fundamental structure-property relationships that define the behavior and utility of new classes of functional materials. For example, recent discoveries in our laboratory demonstrate our ability to tune the magnetic properties of a novel series of insulators; these materials should ultimately find use as magnetoresistive sensors for global positioning/navigation in remote areas. In conjunction with these activities, the proposed educational activities seek to provide training in the interdisciplinary areas of solid state chemistry and condensed matter physics for both undergraduate and graduate students at the University of Houston, which is ranked second among the country's most diverse universities. The PI has established mentoring and volunteer programs from elementary to K-12 levels at schools within the Houston Independent School District. These programs communicate fundamental materials science geared toward understanding scientific aspects of everyday life in experiments and lectures to raise awareness and fascination for next-generation challenges. Furthermore, the PI's activities aim to promote materials science, encompass interaction with young scientists at large, and include international collaborations with highly regarded institutions.

技术摘要：这项由固态与材料化学（SSMC）计划支持的职业计划的目标是了解在存在自旋和轨道自由度的情况下化学压力对几何挫折晶格的影响。 最近发现并随后合成了一系列新的化合物，这些化合物表现出被限制在一个强大的二维构建块中的磁性离子的三角晶格，已经成为一个合适的模板来研究：（1）诱导的轻微结构扭曲的影响和（2）磁相关性对各自自旋系统的依赖性。 一个独特的机会，以获得深入了解调谐铁磁和反铁磁相关介导的超交换途径已经出现了这一系列的化合物。 调查主要是实验性的，包括固态化学合成，光谱，磁化和比热测量。 这项工作的科学影响将有助于从根本上理解几何挫折系统中发生的现象，包括二价和三价3d过渡金属阳离子的自旋轨道耦合方面。 此外，铁磁绝缘体这一高度独特类别的新成员的发现代表了另一个令人兴奋的进展，也是对多功能材料领域的重要贡献。非技术总结：与能源和传感器相关的下一代材料领域的进展依赖于对材料特性的基本理解。此外，设计新的材料类别和控制这些材料的重要功能参数的能力需要详细了解工作机制。 为此，由固态和材料化学计划（SSMC）支持的拟议研究活动的概念框架旨在建立基本的结构-性质关系，以定义新类别功能材料的行为和效用。 例如，我们实验室最近的发现证明了我们有能力调整一系列新型绝缘体的磁特性;这些材料最终应该可以用作偏远地区全球定位/导航的磁阻传感器。 结合这些活动，拟议的教育活动力求为休斯顿大学的本科生和研究生提供固态化学和凝聚态物理学跨学科领域的培训，休斯顿大学在全国最多样化的大学中排名第二。 PI在休斯顿独立学区内的学校建立了从小学到K-12水平的指导和志愿者计划。 这些计划传达基础材料科学，旨在通过实验和讲座了解日常生活的科学方面，以提高对下一代挑战的认识和兴趣。 此外，PI的活动旨在促进材料科学，包括与广大年轻科学家的互动，并包括与备受推崇的机构的国际合作。