Controlling cooperative phenomena in nanomagnetic systems - New physics and its application

这项研究计划将通过以下三个相辅相成的主题，使基于纳米尺度受控磁性的下一代设备和应用成为可能。首先，我的团队将继续开拓合作现象的物理发现，以驱动纳米颗粒制成的大尺寸晶体中的磁性。通过利用自然界固有的机制来驱动纳米颗粒的三维自组装，众所周知的原子的磁性在纳米颗粒中增强了一万倍。我们的工作研究了形成不同晶体结构环境的磁性纳米颗粒的独特性质。晶体中原子间相互作用产生的磁性有序是众所周知的现象。相比之下，在结构有序的纳米颗粒中，磁性在很大程度上是未被探索的。其次，我的团队将研究如何重新获得由于有限尺寸和表面效应造成的磁性损失--特别是在氧化铁和铁氧体基纳米颗粒中普遍存在，这是大量应用物理的基础。表面磁性是无序的，这阻碍了纳米粒子达到最大磁化强度。我们正在通过调整量子限制效应和识别表面和核心原子时刻所经历的合作现象的物理学来发现控制的方法。短期的好处包括使用纳米颗粒作为药物输送的最佳载体，MRI磁性造影剂和改进的磁热疗法。第三，我的团队正在研究铁磁性和反铁磁性(原子尺度上合作现象的两种基本形式)，以及它们在当今技术极限和更远的情况下是如何相互作用的。邻近效应和具有成分和结构限制的部件在纳米尺度的磁性物理中占据主导地位。通过考虑控制磁性属性的方法，如各向异性和磁区配置，我们将对相关设备有更好的了解，如硬盘驱动器读/写头和自旋阀，用于基于自旋电子学的设备。

This research program will make possible the next generation of devices and applications based on controlled magnetism at the nanoscale by following three complementary themes. Firstly, my group will continue to pioneer discoveries into the physics of cooperative phenomena driving magnetism in macro-sized crystals made of nanoparticles. By using nature's inherent mechanisms to drive three-dimensional self-assembly of nanoparticles, the well known atom's magnetism is enhanced by ten-thousand-fold in nanoparticles. Our work investigates the unique properties of magnetic nanoparticles forming different crystal structure environments. Magnetic ordering from interactions between atoms in a crystal is a well understood phenomenon. By contrast, amongst nanoparticles in a structurally ordered configuration, the magnetism is largely unexplored. Secondly, my group will research how to recapture the magnetism lost due to finite size and surface effects - especially prevalent amongst iron-oxide and ferrite-based nanoparticles that are the basis of a large amount of applied physics. Surface magnetism is disordered and this frustrates a nanoparticle from achieving its maximal magnetization. We are discovering ways of control via tuning quantum confinement effects and identifying the physics of the cooperative phenomena that surface and core atomic moments undergo. Short term benefits include using nanoparticles as vehicles optimized for drug delivery, MRI magnetic contrast agents and improved magnetic hyperthermia. Thirdly, my group is investigating ferromagnetism and antiferromagnetism (the two fundamental forms of cooperative phenomena at the atomic-scale) and how they interact at the limit of today's technology and beyond. Proximity effects and parts with compositional and structural constrictions dominate the physics of the magnetism at the nanoscale. By considering ways to control magnetic properties like anisotropy and domain configuration, we will acquire a better understanding of relevant devices such as hard-drive read/write heads and spin-valves used in 'spintronic'-based devices.