HZDR researchers succeed in controlling extremely short-wavelength spin waves
In recent years, electronic data processing has been evolving in one direction only: The industry has downsized its components to the nanometer range. But this process is now reaching its physical limits. Researchers at the Helmholtz-Zentrum Dresden-Rossendorf (HZDR) are therefore exploring spin waves or so-called magnons - a promising alternative for transporting information in more compact microchips. Cooperating with international partners, they have successfully generated and controlled extremely short-wavelength spin waves.
The physicists achieved this feat by harnessing a natural magnetic phenomenon, as they explain in the journal Nature Nanotechnology (DOI: 10.1038/s41565-019-0383-4).
For a long time, there has been one reliable rule of thumb in the world of information technology: The number of transistors on a microprocessor doubles approximately every two years. The resulting performance boost brought us the digital opportunities we now take for granted, from high speed internet to the smartphone.
But as the conductors on the chip get ever more minute, we are starting to face problems, as Dr. Sebastian Wintz from HZDR's Institute of Ion Beam Physics and Materials Research explains: "The electrons that flow through our modern microprocessors heat up the chip due to electrical resistance. Beyond a certain point, the chips simply fail because the heat can no longer escape." This also prevents a further increase in the speed of the components.
This is why the physicist, who is also currently working at the Paul Scherrer Institute (PSI) in Switzerland, envisions a different future for information carriers. Instead of electrical currents, Wintz and his colleagues are capitalizing on a specific property of electrons called 'spin'. The tiny particles behave as if they were constantly rotating around their own axis, thus creating a magnetic moment.
In certain magnetic materials, like iron or nickel, the spins are typically parallel to each other. If the orientation of these spins is changed in one place, that disruption travels to the neighboring particles, triggering a spin wave which can be used to encode and distribute information. "In this scenario, the electrons remain where they are," says Wintz, describing their advantage. "They hardly generate any heat, which means that spin-based components might require far less energy."
How can we control the wave?
So far, however, there have been two fundamental challenges complicating the use of spin waves: The wavelengths that can be generated are not short enough for the nanometer-sized structures on the chips, and there is no way of controlling the waves. Sebastian Wintz and his co-workers have now been able to find solutions to both problems.
"Unlike the artificially made antennas that are commonly employed to excite the waves, we now use one that is naturally formed inside the material," the first author of the study Dr. Volker Sluka explains. "To this end, we fabricated micro-elements comprising two ferromagnetic disks that are coupled antiferromagnetically via a Ruthenium spacer. Furthermore, we chose the material of the disks so that the spins prefer to align along a particular axis in space, which results in the desired magnetic pattern."
Within the two layers, this creates areas of different magnetization, separated by what is called a domain wall. The scientists then exposed the layers to magnetic fields alternating with a frequency of one gigahertz or higher. Using an X-ray microscope from the Max Planck Institute for Intelligent Systems Stuttgart, which is operated at the Helmholtz-Zentrum Berlin, they were able to observe that spin waves with parallel wave fronts travel along the direction perpendicular to the domain wall.
"In previous experiments, the ripples of the wave looked like the ones you get when a pebble hits a water surface," Sluka reports. "This is not optimal, because the oscillation decays quickly as the wave spreads in all directions. To stay in the same analogy, the waves now look as if they were produced by a long rod moving back and forth in the water."
As the X-ray images have shown, these spin waves can travel several micrometers at wavelengths of only about 100 nanometers, without any significant loss of signal - a necessary prerequisite for using them in modern information technology. Moreover, the physicists have discovered a possible way to control this new information carrier when they set the stimulation frequency below half a gigahertz.
The spin waves thus remained trapped in the domain wall: "In this scenario, the waves were even able to run in a curve," says Volker Sluka, adding: "Nevertheless we were still able to detect the signals." With their results, the researchers have laid important foundations for the further development of spin wave-based circuits.
In the long run, this might facilitate a completely novel design of microprocessors, Sebastian Wintz predicts: "Using magnetic fields, we can move domain walls relatively easily. That means that chips that work with spin waves don't necessarily need a predefined architecture, but they can later be changed and adapted to fulfill new tasks."
Publication: V. Sluka, T. Schneider, R.A. Gallardo, A. Kákay, M. Weigand, T. Warnatz, R. Mattheis, A.Roldan-Molina, P. Landeros, V. Tiberkevich, A. Slavin, G. Schütz, A. Erbe, A. Deac, J. Lindner, J. Raabe, J. Fassbender, S. Wintz: Emission and propagation of 1D and 2D spin-waves with nanoscale wavelengths in anisotropic spin textures, in Nature Nanotechnology, 2019 (DOI: 10.1038/s41565-019-0383-4)
For more information contact:
Dr. Sebastian Wintz
Institute of Ion Beam Physics and Materials Research at the HZDR / Paul Scherrer Institute, Switzerland
Phone: + 49 351 260-3221. Email: email@example.com
Dr. Volker Sluka
Institute of Ion Beam Physics and Materials Research at the HZDR
Simon Schmitt | Science editor
Phone: +49 351 260-3400 | Mobile: +49 175 874 2865 | Mail: firstname.lastname@example.org
Helmholtz-Zentrum Dresden-Rossendorf | Bautzner Landstr. 400 | 01328 Dresden / Germany | http://www.
The Helmholtz-Zentrum Dresden-Rossendorf (HZDR) performs - as an independent German research center - research in the fields of energy, health, and matter. We focus on answering the following questions:
To help answer these research questions, HZDR operates large-scale facilities, which are also used by visiting researchers: the Ion Beam Center, the High-Magnetic Field Laboratory Dresden, and the ELBE Center for High-Power Radiation Sources.
HZDR is a member of the Helmholtz Association and has five sites (Dresden, Freiberg, Grenoble, Leipzig, Schenefeld near Hamburg) with almost 1,200 members of staff, of whom about 500 are scientists, including 150 Ph.D. candidates.
Simon Schmitt | EurekAlert!
21.03.2019 | Max-Planck-Institut für Polymerforschung
Levitating objects with light
19.03.2019 | California Institute of Technology
Nano- and microtechnology are promising candidates not only for medical applications such as drug delivery but also for the creation of little robots or flexible integrated sensors. Scientists from the Max Planck Institute for Polymer Research (MPI-P) have created magnetic microparticles, with a newly developed method, that could pave the way for building micro-motors or guiding drugs in the human body to a target, like a tumor. The preparation of such structures as well as their remote-control can be regulated using magnetic fields and therefore can find application in an array of domains.
The magnetic properties of a material control how this material responds to the presence of a magnetic field. Iron oxide is the main component of rust but also...
Due to the special arrangement of its molecules, a new coating made of corn starch is able to repair small scratches by itself through heat: The cross-linking via ring-shaped molecules makes the material mobile, so that it compensates for the scratches and these disappear again.
Superficial micro-scratches on the car body or on other high-gloss surfaces are harmless, but annoying. Especially in the luxury segment such surfaces are...
The Potsdam Echelle Polarimetric and Spectroscopic Instrument (PEPSI) at the Large Binocular Telescope (LBT) in Arizona released its first image of the surface magnetic field of another star. In a paper in the European journal Astronomy & Astrophysics, the PEPSI team presents a Zeeman- Doppler-Image of the surface of the magnetically active star II Pegasi.
A special technique allows astronomers to resolve the surfaces of faraway stars. Those are otherwise only seen as point sources, even in the largest telescopes...
Researchers at Chalmers University of Technology and the University of Gothenburg, Sweden, have proposed a way to create a completely new source of radiation. Ultra-intense light pulses consist of the motion of a single wave and can be described as a tsunami of light. The strong wave can be used to study interactions between matter and light in a unique way. Their research is now published in the scientific journal Physical Review Letters.
"This source of radiation lets us look at reality through a new angle - it is like twisting a mirror and discovering something completely different," says...
New research group at the University of Jena combines theory and experiment to demonstrate for the first time certain physical processes in a quantum vacuum
For most people, a vacuum is an empty space. Quantum physics, on the other hand, assumes that even in this lowest-energy state, particles and antiparticles...
11.03.2019 | Event News
01.03.2019 | Event News
28.02.2019 | Event News
21.03.2019 | Life Sciences
21.03.2019 | Physics and Astronomy
21.03.2019 | HANNOVER MESSE