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

该研究计划将通过以下三个互补主题，使下一代基于纳米级受控磁性的设备和应用成为可能。首先，我的团队将继续探索在由纳米颗粒组成的宏观晶体中驱动磁性的合作现象的物理学发现。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。我们的工作研究了磁性纳米颗粒形成不同晶体结构环境的独特性质。由晶体中原子之间的相互作用产生的磁有序是一种很好理解的现象。相比之下，在结构有序的纳米粒子中，磁性在很大程度上是未开发的。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而失去的磁性-特别是在氧化铁和铁氧体基纳米粒子中，这些纳米粒子是大量应用物理学的基础。表面磁性是无序的，这阻碍了纳米颗粒实现其最大磁化。我们正在通过调整量子限制效应和识别表面和核心原子矩所经历的合作现象的物理学来发现控制方法。短期效益包括使用纳米粒子作为优化的药物输送，MRI磁造影剂和改善磁热疗的车辆。第三，我的小组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及更高水平上如何相互作用。邻近效应和具有成分和结构收缩的部分主导了纳米尺度下的磁性物理。通过考虑控制磁特性（如各向异性和畴结构）的方法，我们将更好地了解相关设备，如硬盘驱动器读/写磁头和基于“自旋电子学”的设备中使用的自旋阀。

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.