Spin Hall voltages from a.c. and d.c. spin currents

• Published in: Nature communications 2014-04, Vol.5 (1), p.3768-3768, Article 3768
• Main Authors: Wei, Dahai, Obstbaum, Martin, Ribow, Mirko, Back, Christian H., Woltersdorf, Georg
• Format: Article
• Language: English
• Subjects: 142/126; 639/766/1130; 639/766/119/1001; Electromagnetic Phenomena; Humanities and Social Sciences; Information Storage and Retrieval - methods; Magnetics; Models, Theoretical; multidisciplinary; Science; Science (multidisciplinary); Time Factors
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/ncomms4768

In spin electronics, the spin degree of freedom is used to transmit and store information. To this end the ability to create pure spin currents—that is, without net charge transfer—is essential. When the magnetization vector in a ferromagnet–normal metal junction is excited, the spin pumping effect leads to the injection of pure spin currents into the normal metal. The polarization of this spin current is time-dependent and contains a very small d.c. component. Here we show that the large a.c. component of the spin currents can be detected efficiently using the inverse spin Hall effect. The observed a.c.-inverse spin Hall voltages are one order of magnitude larger than the conventional d.c.-inverse spin Hall voltages measured on the same device. Our results demonstrate that ferromagnet–normal metal junctions are efficient sources of pure spin currents in the gigahertz frequency range. A spin current is injected from a ferromagnet into a nonmagnetic metal at magnetic resonance. Here, the authors show that this current has both a direct-current and a much larger alternating-current component, indicating that these structures could be useful for high-frequency spintronics.