Magnetic nanocontacts propagate spin waves, prove magnonics researchers

September 12, 2011 — University of Gothenburg and the Royal Institute of Technology (KTH) researchers demonstrated that theories about nanoscale spin waves agree with observations — potentially replacing microwave technology in many applications, such as mobile phones and wireless networks. The "magnonics" phenomenon could lead to smaller and cheaper components.

The group demonstrated that spin waves propagated from magnetic nanocontacts, observing the dynamic properties via an advanced spin wave microscope (based at the University of Perugia, Italy) with a resolution of approximately 250nm. The observations were enabled by their method of constructing the magnetic nanocontacts. The research field has been named "magnonics," meaning the understanding and use of nanoscale magnetic waves.

In 2010, the group was able to demonstrate the existence of spin waves with the aid of electrical measurements (published, Physical Review Letters). The researchers competed with two other groups to confirm experimentally theoretical predictions that came to light about a decade ago, said Professor Johan Åkerman of the Department of Physics, University of Gothenburg, where he is head of the Applied Spintronics group.

Magnonic components and circuits are "powered by simple direct current, which is then converted into spin waves in the microwave region. The frequency of these waves can be directly controlled by the current. This will make completely new functions possible," says Åkerman. Magnonic technology boasts magneto-optical and metallic properties that will work with traditional microwave-based electronic circuits, and also suit more minaturization.

Results have been published in Nature Nanotechnology: "Direct observation of a propagating spin wave induced by spin-transfer torque." Access it here:

Animated simulations of spin waves are available on the researchers’ YouTube channel: A simulation of six magnetic nanocontacts placed in a circle to illustrate how the nanocontacts can be placed in freely chosen patterns. All the signals synchronize in this case through the spin waves that propagate through the magnetic film. The simulation of magnetic nanocontacts shows how spin waves spread like rings on water. The nanocontact has a diameter of 40 nanometer and the spin waves are created in a thin film of nickel-iron alloy, 3 nanometer thick.


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