Exploring new functionalities of magnetic materials utilizing nanoplasmonics and multiferroics

利用纳米等离子体和多铁性探索磁性材料的新功能

• 批准号: RGPIN-2018-03765
• 负责人: Choi, ByoungChul
• 金额: $ 2.04万
• 依托单位: University of Victoria
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2020
• 资助国家: 加拿大
• 起止时间: 2020-01-01 至 2021-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=712549
• 关键词: Exploring; new; functionalities; magnetic; materials

The purpose of this proposal is to explore new functionalities of magnetic materials utilizing nanoplasmonics and multiferroics. In particular, we are interested in developing new ways to control magnetism optically or electrically. In the first part of the research, we will investigate the interaction between light and magnetism, which is of utmost importance in terms of fundamental science and technological applications. A specific goal is the ultrafast light control of magnetism. The strength of the interaction of light with a magnetic medium, however, is very weak, and this weak interaction has been the main challenge in optically probing or controlling magnetism. In order to overcome this drawback, we will exploit magneto-plasmonics, which combines magnetic and plasmonic functionalities. In our previous studies, we observed that the incorporation of noble-metal nanoparticles in ferromagnetic films significantly enhances magneto-optical (MO) effect. We will conduct systematic studies on the influence of plasmon resonance on MO effect, and develop a better understanding of the underlying mechanism of the enhanced MO activities. We will also study the ultrafast magnetism triggered by optically excited high energy electrons. The questions to be answered are: can we enhance the optical generation of hot electrons via localized surface plasmon resonance? If so, how effectively can we manipulate the hot-electron induced ultrafast magnetic process? Another project is to generate large wavenumber spin waves using ultrafast optical excitation. It is known that the spin wavenumber is determined by the spatial intensity distribution of the pumping light. We will be able to reduce the pump spot size to the nanoscale by using near-field optics. Higher spin wavenumbers can also be generated by using the localized surface plasmon resonance, in which the spatial intensity distribution is determined by the geometries of the nanoparticles. The second part of the research is to explore the opportunity of electric-field control of magnetism utilizing magnetoelectric multiferroics, which enables the coupling between magnetic and ferroelectric orders. However, room temperature multiferroics are very rare, with BiFeO3 (BFO) being an exception. Its drawback is that it has a very weak magnetic moment. Recently, it was found that a double perovskite material Bi2FeCrO6 (BFCO) has ferroelectricity similar to BFO with the added benefit of a strong magnetic moment. Our main goal is to answer the question whether BFCO can provide a new avenue for electric-field switching of magnetism. We will also investigate the electric-field triggered magnetization dynamics in gated BFCO thin films. Considering that the electric-field control of magnetism enabled by multiferroics has the potential to revolutionize today's electronics technology, the outcome of the proposed research will be significant.

这项建议的目的是探索利用纳米等离子体和多铁性的磁性材料的新功能。特别是，我们对开发光学或电子控制磁性的新方法感兴趣。 在研究的第一部分，我们将研究光和磁之间的相互作用，这在基础科学和技术应用方面是非常重要的。一个具体的目标是磁性的超快光控制。然而，光与磁性介质的相互作用强度很弱，这种微弱的相互作用一直是光学探测或控制磁性的主要挑战。为了克服这一缺点，我们将利用磁等离子体激元，它结合了磁和等离子激元的功能。在我们以前的研究中，我们观察到在铁磁薄膜中掺入贵金属纳米颗粒显著地增强了磁光效应。我们将对等离子体共振对MO效应的影响进行系统的研究，并更好地理解MO活性增强的潜在机制。我们还将研究由光激发的高能电子引发的超快磁性。需要回答的问题是：我们能否通过局域表面等离子体共振来增强热电子的光学产生？如果是这样的话，我们能如何有效地操纵热电子诱导的超快磁过程？另一个项目是利用超快光激发产生大波数的自旋波。众所周知，自旋波数是由泵浦光的空间强度分布决定的。我们将能够通过使用近场光学将泵浦光斑的尺寸减小到纳米级。利用局域表面等离子体共振也可以产生更高的自旋波数，其中空间强度分布由纳米粒子的几何形状决定。 研究的第二部分是探索利用磁电多铁体实现磁和铁电有序耦合的电场控制磁体的机会。然而，室温多铁体非常罕见，BiFeO_3(BFO)是一个例外。它的缺点是它的磁矩非常弱。最近，人们发现一种双钙钛矿材料Bi2FeCrO6(BFCO)具有类似于BFO的铁电性，并增加了强磁矩的好处。我们的主要目标是回答BFCO能否为磁场的电场转换提供一种新的途径的问题。我们还将研究栅控BFCO薄膜的电场触发磁化动力学。考虑到多铁性对磁场的电场控制有可能给当今的电子技术带来革命性的变化，拟议中的研究成果将是重要的。