Berlin 2005 – wissenschaftliches Programm

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TT: Tiefe Temperaturen

TT 19: Transport - Nanoelectronics I: Spintronics and Magnetotransport

TT 19.5: Hauptvortrag

Montag, 7. März 2005, 11:00–11:30, TU H3027

Spin Pumping in a Mesoscopic Spin Battery — •Bart van Wees — Department of Applied Physics and Materials Science Center, University of Groningen, The Netherlands

In the field of spintronics it has become possible to generate, study, and employ phenomena like spin currents and spin accumulation. A very new and exciting development is to use the fact that a spin current represents a flow of angular momentum. A new prediction [1] concerns a ferromagnetic island of which the magnetization direction is made to precess using ferromagnetic resonance, by driving it with a RF magnetic field with frequencies in the gigahertz range. It is predicted that as a result a spin current can be emitted into the non-magnetic metal or semiconductor which is attached to this ferromagnet. The ferromagnet will therefore act as a "spin battery", which can supply energy, not by an electronic charge current, but by a spin current. In this talk I will give a introduction into the relevant concepts for this phenomenon, including spin injection, spin mixing, spin transport and spin pumping. I will then discuss some of our recent experiments which show how spin accumulation can be created and studied in mesoscopic devices[2], and experiments [3] which show that spin currents are created by a "mesoscopic spin battery" by driving a micrometer sized ferromagnet with a strong RF field, generated by an "on-chip" microwave circuit close to the mesoscopic device structure. [1] Y. Tserkovnyak et al., Phys. Rev. Lett. 88, 117601 (2002) [2] M. Zaffalon, and B.J. van Wees, Phys. Rev. Lett. 91, 186601 (2003) [3] M. Costache et al., in preparation