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

摘要本课题研究了用光刻方法制备纳米级磁体阵列的排列和性能。基础物理组件将通过实验和建模来研究这些阵列的稳定磁结构，这些阵列受到不同磁底层引入的不同扰动。它还将研究(a)将这种阵列用于下一代磁记录介质用于信息存储的可能性，以及(b)开发用于信息处理中逻辑功能的磁方法。我们将研究能够提供更多自由来设计新属性、功能和应用程序的交互。该提案还将使PI能够将发现的同步推进与教学、培训、学习以及适当的商业化结合起来。技术摘要：单畴纳米级磁性元件，通过光刻技术制造，并形成有序阵列，形成具有不同寻常性能的优异磁性超材料。通常，它们的行为是由宏观元素间的偶极相互作用主导的，但在这里，我们提出微观交换相互作用，以提供急需的额外自由，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级铁磁岛晶格中的几何挫败，导致自旋冰构型的形成；在这里，我们建议研究自旋冰超材料的材料物理和磁构型，包括其热力学相变，通过底层耦合，其中自旋晶格的纳米元素之间的相互作用由侧向交换偏置（EB）主导。在自旋-冰构型演化的不同阶段，也可以沿着不同的明确的晶体学方向添加EB。(2)或者，超材料中的每个元素可以是多层的，具有元素内部交换相互作用；这种交换耦合复合材料，通过纳米压印技术在大面积阵列中制造，其磁性能将在位图型介质中得到优化。(3)磁性量子元胞自动机（MQCA）在特定的纳米磁阵列中处理信息并执行布尔逻辑运算是CMOS技术的一个有前途的替代方案。我们将首次设计和构建基于新颖设计的低于50nm的纳米磁铁元件，执行基本布尔逻辑运算的交换耦合逻辑门；将演示两个具有代表性的门（AND和OR）。微磁建模和材料表征，包括常规的和先进的，使用电子，光子和扫描探针，将提供基本的洞察结构-性能的相关性，在适当的长度尺度，所有这些独特的和定制的超材料。该提案还将使PI能够将发现的同步推进与教学、培训、学习以及适当的商业化结合起来。

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.