Current generated by rotating magnetisation

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An international research team, including the Norwegian University of Science and Technology (NTNU) and the University of Cambridge, has demonstrated that it is possible to generate an electric current in a magnetic material by rotating its magnetisation.

This link between magnetism and electricity may have applications in electronics, says the team, including ways of transferring and manipulating data based on spintronics. "Much of the progress in spintronics has resulted from exploiting the coupling between the electron spin and its orbital motion," said Professor Arne Brataas from NTNU. "But our understanding of these interactions is still immature; we need to know more so that we can fully explore and exploit these forces." It has been known for some time that rotating the magnetisation in a magnetic material can generate pure spin currents in adjacent conductors. However, these cannot be detected conventionally using a voltmeter and a secondary spin-charge conversion element is needed, such as another ferromagnet. However, Prof Brataas and his collaborators have demonstrated that in a small class of ferromagnetic materials, spin-charge conversion occurs in the materials themselves. The spin currents created in these materials are converted directly to charge currents via spin-orbit interaction. In other words, the ferromagnets function as AC generators, driven by the rotating magnetization. "The phenomenon is a result of a direct link between electricity and magnetism. It allows for the possibility of new nano-scale detection techniques of magnetic information and for the generation of very high-frequency alternating currents," Prof Brataas concluded.