Spin Transfer Torque in Ferromagnetic Semiconductors and Hybrid Devices for Nanospintronics

利用电流控制磁性是快速发展的纳米自旋电子学研究领域的一个中心活动。这种被称为自旋转移扭矩的基本机制提供了对电荷和自旋相互作用的全新见解，并为新的高密度存储设备、非易失性存储器以及微波发射器和过滤器的前景提供了新的前景。这里的一个关键挑战是在保持热稳定性的同时将所需的临界电流的大小降至最低。最近已经证明，在以III-V化合物为基础的铁磁半导体材料中，所需的临界电流可以比金属中的低一个数量级。这些材料还提供了精确调整和控制其性质的能力，使铁磁性半导体形成了一个理想的试验场，以加强对自旋转移扭矩和相关影响的了解。这项建议是一个广泛的3年合作研究计划，旨在研究自旋电子器件中电荷和自旋相互作用和输运的基本原理，以及纳米自旋内子器件的潜力，为未来的电子学提供一个新的范例。我们主要研究电流与纳米线和隧道结构中的局域自旋之间的相互作用。通过这个项目，我们将开发新的器件结构，以解决技术上的重要问题，包括自旋-轨道耦合所起的作用以及与半导体技术的兼容性。这个项目的一个特别新颖的方面是，它利用铁磁半导体系统的极端灵活性来理解这些效应的基本原理，同时也在室温铁磁金属系统中探索它们。该项目汇集了英国领先的半导体自旋电子学研究小组和中国的互补专业知识，在加强现有合作的同时坚定地建立了新的合作，并利用了每个参与者在最先进的材料开发和新器件概念方面的最新成果。

The control of magnetic properties using electrical currents is a central activity in the fast-moving research field of nanospintronics. The underlying mechanism, called spin-transfer torque, offers fundamentally new insights into the interactions of charge and spin as well as prospects for new high-density storage devices, non-volatile memories and microwave emitters and filters. A key challenge here is to minimise the magnitude of the critical currents required while maintaining thermal stability. It has recently been demonstrated that, in ferromagnetic semiconducting materials based on III-V compounds, the critical currents required can be orders of magnitude lower than in metals. These materials also offer the ability to precisely tune and control their properties, so that ferromagnetic semiconductors form an ideal testing ground for enhancing the understanding of spin transfer torque and related effects.This proposal is for an extensive 3 year collaborative programme of research which aims to investigate aspects of both the fundamentals of charge and spin interactions and transport in spintronic devices and the potential of nanospintronic devices to provide a new paradigm for future electronics. We focus on the interaction between an electrical current and local spins in nanowires and tunnelling structures. Through this project we will develop novel device structures in order to address open questions of technological importance, including the role played by spin-orbit coupling and the compatibility with semiconductor technology. A particularly novel aspect of this project is that it exploits the extreme flexibility of ferromagnetic semiconductor systems to understand the fundaments of these effects while also exploring them in room temperature ferromagnetic metal systems. The project brings together complementary expertise of leading semiconductor spintronics research groups in the UK and China, firmly establishing a new collaboration while also strengthening existing ones, and exploits recent achievements by each participant in state-of-the-art materials development and new device concepts.