New Materials for Quantum Magnetism: Spin Dimer Compounds

量子磁性新材料：自旋二聚体化合物

• 批准号: 0705087
• 负责人: Ian Fisher
• 金额: $ 35万
• 依托单位: Stanford University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2007
• 资助国家: 美国
• 起止时间: 2007-05-01 至 2010-04-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0705087&HistoricalAwards=false
• 关键词: New; Materials; Quantum; Magnetism; Spin

Technical:This individual investigator award supports experimental studies in the field of quantum magnetism, and specifically investigation of the high-field ordered states of spin dimer compounds. These materials comprise strongly coupled pairs of spins (dimers) which by virtue of the crystal structure only weakly interact with each other. For antiferromagnetic intradimer exchange the ground state is a product of singlets, but strong magnetic fields can close the spin gap to excited triplet states which are delocalized as a consequence of interdimer coupling. These systems provide an elegant realization of a lattice gas of hardcore bosons, in which the external magnetic field plays the role of the chemical potential and the interdimer interactions determine both the kinetic and potential energy of the delocalized triplets. Depending on the balance of the interdimer couplings the triplets either crystallize or condense at low temperatures, leading to qualitatively different magnetically ordered states. Despite considerable theoretical interest in these magnetic states, there are relatively few candidate materials. The aim of this new research program is to develop novel spin dimer compounds, the study of which will deepen our understanding of the magnetically ordered states of this unusual class of materials. Experiments performed both in the PIs laboratory and at national facilities probe the magnetic properties via both thermodynamic and scattering measurements. Materials developed as part of this program will be available to the broader US condensed matter community via collaboration. Students involved in this work will graduate skilled in experimental studies of magnetism and the science and art of crystal growth. Non-technical:The search for and discovery of new materials plays a vital role in the field of condensed matter physics and in the development of advanced technologies. This award funds a program that is focused on the development of new materials with novel magnetic properties. The study of magnetism and magnetic materials dates back to antiquity, but many fundamental questions remain unanswered about the ways in which atomic magnetic moments arrange themselves (i.e. order) with respect to each other at low temperatures. The scientific goal of this program is to understand the magnetically ordered states of spin dimer compounds, a novel class of magnetic material which provides some unique perspectives on magnetism and magnetic structures. Despite considerable theoretical interest in this area, and some natural advantages of these systems for studying specific aspects of magnetically ordered structures, there are relatively few candidate materials. The emphasis of this award is on the synthesis and characterization of new examples of spin dimer compounds. Experiments performed both in the PIs laboratory and at national facilities probe the magnetic properties of these materials via both thermodynamic and scattering measurements. Materials developed as part of this program will be available to the broader US condensed matter community via collaboration. Students involved in this work will graduate skilled in experimental studies of magnetism and the science and art of crystal growth.

技术：该个人研究者奖支持量子磁学领域的实验研究，特别是自旋二聚体化合物的高场有序态的研究。这些材料包括强耦合的自旋对（二聚体），由于晶体结构，它们之间的相互作用很弱。对于反铁磁内交换体，基态是单重态的产物，但强磁场可以关闭自旋间隙到激发态，激发态由于中间二聚体耦合而离域。这些系统提供了核核玻色子晶格气体的优雅实现，其中外部磁场起化学势的作用，中间二聚体相互作用决定了离域三重态的动能和势能。根据中间二聚体耦合的平衡，三元态在低温下结晶或凝聚，从而导致不同性质的磁有序态。尽管对这些磁态有相当大的理论兴趣，但候选材料相对较少。这项新研究计划的目的是开发新的自旋二聚体化合物，对其的研究将加深我们对这类不寻常材料的磁有序态的理解。在PIs实验室和国家设施进行的实验通过热力学和散射测量来探测磁性。作为该计划一部分开发的材料将通过合作提供给更广泛的美国凝聚态物质社区。参与这项工作的学生毕业时将熟练掌握磁性实验研究以及晶体生长的科学和艺术。非技术：寻找和发现新材料在凝聚态物理领域和先进技术的发展中起着至关重要的作用。该奖项资助了一个专注于开发具有新型磁性质的新材料的项目。对磁学和磁性材料的研究可以追溯到古代，但关于原子磁矩在低温下相互排列（即顺序）的方式，许多基本问题仍未得到解答。该计划的科学目标是了解自旋二聚体化合物的磁性有序态，这是一类新的磁性材料，为磁性和磁性结构提供了一些独特的视角。尽管在这一领域有相当大的理论兴趣，并且这些系统在研究磁性有序结构的特定方面具有一些天然优势，但候选材料相对较少。这个奖项的重点是合成和表征自旋二聚体化合物的新例子。在PIs实验室和国家设施进行的实验通过热力学和散射测量来探测这些材料的磁性。作为该计划一部分开发的材料将通过合作提供给更广泛的美国凝聚态物质社区。参与这项工作的学生毕业时将熟练掌握磁性实验研究以及晶体生长的科学和艺术。