Overtones can provide faster data communication

January 10, 2019, University of Gothenburg
The following illustration shows how the microwave signal jumps from about 10 GHz to 14 GHz and then to 20 GHz when the current is increased. Credit: Johan Åkerman/The University of Gothenburg

For the first time, researchers have succeeded in producing what are known as spin wave overtones. The technology paves the way for increasing the data transmission rate of wireless communication.

Spintronic oscillators are nano-components in which spin waves are used to generate microwave signals in the gigahertz range. Spin wave overtones can be compared to the overtones (flageolets) that are used in music.

"For example, an experienced violinist knows exactly where to carefully place the finger on the string to dampen the fundamental frequency and instead allow the string to oscillate at one of its many overtones. This makes it possible to play tones that are much higher in frequency than the string's fundamental tone," says Johan Åkerman, a professor at the University of Gothenburg.

Along with colleagues in Gothenburg and Portugal, he has now demonstrated how to play and strengthen such overtones at the nano level. The researchers have produced spintronic oscillators that strengthen spin wave signals in several steps.

Surprising results

To the researchers' surprise, their new oscillators proved to be a completely unexpected and new phenomenon.

When the researchers increased the drive current, the signal showed a sharp jump in frequency: first, from the fundamental frequency of 9 GHz to 14 GHz and then a second jump to 20 GHz.

Portrait of Johan Åkerman. Credit: Johan Wingborg.
"The results are consistent with John Slonczewski's forgotten theoretical predictions of spin wave overtones," says Åkerman.

In a 1999 article, physicist Slonczewski described the basis of spin waves generated in spin electronic oscillators. He mentioned that his model also supports the generation of much higher frequencies using overtones.

"While John Slonczewski's article inspired a rapidly growing research field within spintronic oscillators, there have been no further discussions of overtones at all, nor have they been tested experimentally until now. Our experiment shows that it is possible to create several different overtones in oscillators, which permits extremely large and fast frequency jumps to increase the data transmission rate of wireless communication."

The discovery also makes it possible for researchers to generate very high microwave frequencies with short wavelengths for use in spintronics and magnonics.

"While the wavelength of the fundamental tone is about 500 nanometres, the wavelength of the demonstrated third overtone is as short as 74 nanometres. Future studies on smaller oscillators should be able to generate spin waves down to 15 nanometres with frequencies up to 300 GHz. That is why the potential for extremely high-frequency spintronics and is enormous," says Åkerman.

Higher leads to faster data communication in wireless transmission, but it can also provide better automotive radar for self-driving cars

The article was recently published in Nature Communications.

Explore further: Researchers create focused spin wave beams

More information: A. Houshang et al, Spin transfer torque driven higher-order propagating spin waves in nano-contact magnetic tunnel junctions, Nature Communications (2018). DOI: 10.1038/s41467-018-06589-0

Related Stories

Researchers create focused spin wave beams

December 22, 2015

Researchers at the University of Gothenburg Physics Department have finally found the secret to synchronize an unlimited number of spintronic oscillators. Such devices are very promising for future applications requiring ...

Making spintronic neurons sing in unison

November 16, 2016

What do fire flies, Huygens's wall clocks, and even the heart of choir singers, have in common? They can all synchronize their respective individual signals into one single unison tone or rhythm.

Nano-Signals Get a Boost from Magnetic Spin Waves

August 31, 2006

Researchers have figured out how nanoscale microwave transmitters gain greater signal power than the sum of their parts—a finding that will help in the design of nano-oscillator arrays for possible use as transmitters and ...

Researchers take magnetic waves for a spin

January 29, 2014

Researchers at New York University have developed a method for creating and directing fast moving waves in magnetic fields that have the potential to enhance communication and information processing in computer chips and ...

Optical 'overtones' for solar cells

April 19, 2018

NIM scientists from LMU Munich have found a new effect regarding the optical excitation of charge carriers in a solar semiconductor. It could facilitate the utilization of infrared light, which is normally lost in solar devices.

Recommended for you

ATLAS experiment observes light scattering off light

March 20, 2019

Light-by-light scattering is a very rare phenomenon in which two photons interact, producing another pair of photons. This process was among the earliest predictions of quantum electrodynamics (QED), the quantum theory of ...

How heavy elements come about in the universe

March 19, 2019

Heavy elements are produced during stellar explosion or on the surfaces of neutron stars through the capture of hydrogen nuclei (protons). This occurs at extremely high temperatures, but at relatively low energies. An international ...

Trembling aspen leaves could save future Mars rovers

March 18, 2019

Researchers at the University of Warwick have been inspired by the unique movement of trembling aspen leaves, to devise an energy harvesting mechanism that could power weather sensors in hostile environments and could even ...

Quantum sensing method measures minuscule magnetic fields

March 15, 2019

A new way of measuring atomic-scale magnetic fields with great precision, not only up and down but sideways as well, has been developed by researchers at MIT. The new tool could be useful in applications as diverse as mapping ...

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.