Spintronics boosted by efficient pumping technique

Researchers at Tohoku University on Japan and Delft University of Technology and Science in The Netherlands have experimentally demonstrated “an unprecedented level of control” of pumping electron spins, according to an article published in the 23 May edition of the APS journal Physics Review Letters.

In the article abstract, they explain: "We experimentally show that exchange magnons can be detected by using a combination of spin pumping and the inverse spin-Hall effect proving its wavelength integrating capability down to the submicrometer scale."

An accompanying analysis notes that the material used, the ferromagnet yttrium iron garnet (YIG), is a promising material for future spin-based electronics, "where its wires could be used as interconnects between processing and data-storage modules".

Spin-pumping might sound like something a particularly sadistic fitness fanatic might come up with, but in fact it is how one transports the angular momentum of electrons "by moving an equal number of up and down spins in opposite directions", and thus is the key to spintronics.

Spintronics promises to revolutionise electronics, especially information transmission systems, and make possible highly efficient technologies. The analysis explains that although current silicon CMOS technology will never be able to compete with the potential of spintronics, finding an efficient way to control the movement of spin has been challenging.

"In metals, spin currents heat the material through which they propagate just as charge currents do. In magnetic insulators, on the other hand, charge currents simply do not exist, while spin currents can still be transmitted with very little dissipation. However, the efficiency of spin current actuation and detection remains an issue."

But the newly demonstrated technique "spin pumping by parametrically excited exchange magnons", could be a step in the right direction. Although the researchers concerned themselves solely with spin-pumping readout, the reverse operation should be possible.

The article concludes: "Ultimately, the present results are a step forward in the development of, under ambient conditions, energy-efficient spin-based electronics that does not require itinerant charge carriers."