Spin Transfer Torque in Ferromagnetic Semiconductors and Hybrid Devices for Nanospintronics

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.