Exchange-coupled magnetic metamaterials: fabrication, structure-property correlations, and applications

非技术摘要本项目介绍了用光刻方法制备的纳米级磁体阵列的排列和性质。基础物理部分将通过实验和建模来研究这种阵列在不同磁性底层引入的不同扰动下的稳定磁构型。它还将研究(A)将这种阵列用于信息存储的下一代磁记录介质的可能性，以及(B)开发一种用于信息处理中的逻辑功能的磁方法。我们将研究能够提供迫切需要的额外自由来设计新特性、功能和应用的相互作用。这项建议还将使PI能够将发现的同时发展与教学、培训、学习结合起来，并在适当的情况下实现商业化。技术摘要通过光刻制造的单域、纳米尺度的磁性元件，并图案化成有序的阵列，形成具有特殊性能的优异的磁性超材料。通常，它们的行为是由宏观的元素间偶极相互作用主导的，但在这里，我们提出了微观交换相互作用，以提供迫切需要的额外自由，以在三个不同的领域设计新的性质、功能和应用：(1)具有偶极相互作用的纳米铁磁岛的晶格中的几何受挫，导致自旋-冰结构的形成；在这里，我们建议研究自旋-冰超材料的材料物理和磁结构，包括它的热力学相变，通过底层耦合，其中针销晶格的纳米元素之间的相互作用是由横向交换偏置(EB)主导的。在自旋-冰态演化的不同阶段，沿着不同晶向的EB也可以加入到体系中。(2)或者，超材料中的每个元素可以是多层的，具有元素内的交换作用；利用纳米压印光刻技术在大面积阵列中制备的交换耦合复合材料的磁性能将针对位图案化介质进行优化。(3)在特定的纳米磁阵列中使用磁量子细胞自动机(MQCA)来处理信息和执行布尔逻辑运算是一种很有前途的替代CMOS技术的方法。我们将首次基于一种新的亚50 nm纳米磁元件设计和构造执行基本布尔逻辑运算的交换耦合逻辑门；两个代表性的门(AND和OR)将被展示。使用电子、光子和扫描探针的常规和高级的微磁建模和材料表征，将在适当的长度尺度上提供对所有这些独特的和定制的超材料的结构-性质性能关联的基本洞察。这项建议还将使国际和平研究所能够将发现的同时进步与教学、培训和学习结合起来，并在适当的情况下实现商业化。

Non-Technical AbstractThis project addresses the arrangement and properties of arrays of nanoscale magnets fabricatedby lithography methods. The fundamental physics component will investigate, both byexperiment and modeling, the stable magnetic configuration of such arrays subject to differentperturbations introduced by different magnetic underlayers. It will also investigate the possibilityof (a) using such arrays for next generation magnetic recording media for information storage, and(b) developing a magnetic approach for logic function in information processing. We will study interactions that can provide much needed additional freedom toengineer new properties, functionalities and applications. This proposal will also enable the PI to combine the simultaneous advancement of discovery with teaching, training, learning, and if appropriate, commercialization. Technical AbstractSingle domain, nanoscale magnetic elements, fabricated by lithography, and patterned intoordered arrays, form excellent magnetic metamaterials with unusual properties. Typically, theirbehavior is dominated by macroscopic inter-element dipolar interactions, but here in addition, wepropose microscopic exchange interactions to provide much needed additional freedom toengineer new properties, functionalities and applications in three distinct areas:(1) Geometrical frustration in a lattice of nanoscale ferromagnetic islands with dipolar interactions,leads to the formation of a spin-ice configuration; here we propose to investigate the materialsphysics and magnetic configuration of a spin-ice metamaterial, including its thermodynamic phasetransitions, coupled through underlayers where the interactions between the nanoelements of thespin lattice are dominated by lateral exchange bias (EB). The EB, along different well-definedcrystallographic directions, can also be added to the system at different stages of the spin-iceconfigurational evolution.(2) Alternatively, each element in the metamaterial can be a multilayer, with intra-elementexchange interactions; the magnetic performance of such exchange exchange-coupled compositemetamaterial, fabricated in large-area arrays by nanoimprint lithography, will be optimized for bitpatternedmedia.(3) Magnetic quantum cellular automata (MQCA) in specific nanomagnetic arrays to processinformation and perform Boolean logic operations is a promising alternative to CMOS technology.We will design and construct, for the first time, exchange-coupled logic gates that performelementary Boolean logic operations, based on a novel design of sub-50nm nanomagnet elements;two representive gates (AND and OR), will be demonstrated.Micromagnetic modeling and materials characterization, both routine and advanced, usingelectrons, photons and scanning probes, will provide fundamental insight into the structure- property performance correlation, at appropriate length scales, of all these unique and tailoredmetamaterials. This proposal will also enable the PI to combine the simultaneousadvancement of discovery with teaching, training, learning, and if appropriate, commercialization.