Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Curved kick on the nanoscale: Investigations of the skyrmion Hall effect reveal surprising results

27.12.2016

One step further towards the application of skyrmions in spintronic devices

Researchers at Johannes Gutenberg University Mainz (JGU) and the Massachusetts Institute of Technology (MIT) have made another important breakthrough in the field of future magnetic storage devices. Already in March 2016, the international team investigated structures, which could serve as magnetic shift register or racetrack memory devices. This type of storage promises low access times, high information density, and low energy consumption. Now, the research team achieved the billion-fold reproducible motion of special magnetic textures, so-called skyrmions, between different positions, which is exactly the process needed in magnetic shift registers thereby taking a critical step towards the application of skyrmions in devices. The work was published in the research journal Nature Physics.


The magnetic structure of a skyrmion is symmetrical around its core; arrows indicate the direction of spins.

ill./©: Benjamin Krüger, JGU

The experiments were carried out in specially designed thin film structures, i.e., vertically asymmetric multilayer devices exhibiting broken inversion symmetry and thus stabilizing special spin structures called skyrmions. Those structures are similar to a hair whorl and like these are relatively difficult to destroy. This grants them unique stability, which is another argument for the application of skyrmions in such spintronic devices.

Since skyrmions can be shifted by electrical currents and feel a repulsive force from the edges of the magnetic track as well as from single defects in the wire, they can move relatively undisturbed through the track. This is a highly desired property for racetrack devices, which are supposed to consist of static read- and write-heads, while the magnetic bits are shifted in the track. However, it is another important aspect of skyrmion dynamics that the skyrmions do not only move parallel to the applied current, but also perpendicular to it. This leads to an angle between the skyrmion direction of motion and the current flow called the skyrmion Hall angle, which can be predicted theoretically. As a result, the skyrmions should move under this constant angle until they start getting repelled by the edge of the material and then keep a constant distance to it.

Within their latest research project, scientists of JGU and MIT now proved that the billion-fold reproducible displacement of skyrmions is indeed possible and can be achieved with high velocities. Furthermore, the skyrmion Hall angle was investigated in detail. Surprisingly, it turned out to be dependent on the velocity of the skyrmions, which means that the components of the motion parallel and perpendicular to the current flow do not scale equally with the velocity of the skyrmions. This is not predicted in the conventional theoretical description of skyrmions. Part of the solution of this unexpected behavior could be the deformation of the skyrmion spin structure, calling for more theoretical effort to fully understand the properties of skyrmions.

"I am glad that the collaboration between Mainz University and MIT has already yielded the second high-ranked publication. Considering especially the short time since the collaboration started, this is exceptional and I am happy to be able to participate in it," said Kai Litzius, first-author of the Nature Physics article. Litzius is a scholar of the Graduate School of Excellence "Materials Science in Mainz" (MAINZ) and a member of the team headed by Professor Mathias Kläui.

"In highly competitive fields of research such as that on skyrmions, international cooperation with leading groups is a strategical advantage. Within only two years after the start of the collaboration with our colleagues from MIT, we have already published the second time together in a high-ranked Nature group journal. The MAINZ Graduate School of Excellence facilitates research stays of PhD students from the United States in Mainz and vice versa and therefore contributes significantly to international education and successful research in this field,” emphasized Professor Mathias Kläui of the JGU Institute of Physics, who is also Director of MAINZ.

Establishment of the MAINZ Graduate School was granted through the Excellence Initiative by the German Federal and State Governments to Promote Science and Research at German Universities in 2007 and its funding was extended in the second round in 2012. It consists of work groups from Johannes Gutenberg University Mainz, TU Kaiserslautern, and the Max Planck Institute for Polymer Research in Mainz. One of its focal research areas is spintronics, where cooperation with leading international partners plays an important role.

Publication:
Kai Litzius et al.
Skyrmion Hall effect revealed by direct time-resolved X-ray microscopy
Nature Physics, 26 December 2016
DOI: 10.1038/nphys4000


Further information:
Professor Dr. Mathias Kläui
Condensed Matter Theory Group
Institute of Physics
Johannes Gutenberg University Mainz
55099 Mainz, GERMANY
phone +49 6131 39-23633
e-mail: klaeui@uni-mainz.de
http://www.klaeui-lab.physik.uni-mainz.de

Graduate School of Excellence "Materials Science in Mainz" (MAINZ)
Johannes Gutenberg University Mainz
55099 Mainz, GERMANY
phone +49 6131 39-26984
fax +49 6131 39-26983
e-mail: mainz@uni-mainz.de
http://www.mainz.uni-mainz.de/

Weitere Informationen:

http://www.nature.com/nphys/journal/vaop/ncurrent/full/nphys4000.html – Abstract ;
http://www.uni-mainz.de/presse/20165_ENG_HTML.php – press release “International research team achieves controlled movement of skyrmions” (7 March 2016) ;
http://www.uni-mainz.de/presse/18027_ENG_HTML.php – press release “Physicists observe motion of tiny magnetic whirls” (3 March 2015)

Petra Giegerich | idw - Informationsdienst Wissenschaft

More articles from Physics and Astronomy:

nachricht Good vibrations feel the force
23.02.2018 | Max-Planck-Institut für Struktur und Dynamik der Materie

nachricht Researching the LED Wallpaper of the Future
23.02.2018 | Universität Bremen

All articles from Physics and Astronomy >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Developing reliable quantum computers

International research team makes important step on the path to solving certification problems

Quantum computers may one day solve algorithmic problems which even the biggest supercomputers today can’t manage. But how do you test a quantum computer to...

Im Focus: In best circles: First integrated circuit from self-assembled polymer

For the first time, a team of researchers at the Max-Planck Institute (MPI) for Polymer Research in Mainz, Germany, has succeeded in making an integrated circuit (IC) from just a monolayer of a semiconducting polymer via a bottom-up, self-assembly approach.

In the self-assembly process, the semiconducting polymer arranges itself into an ordered monolayer in a transistor. The transistors are binary switches used...

Im Focus: Demonstration of a single molecule piezoelectric effect

Breakthrough provides a new concept of the design of molecular motors, sensors and electricity generators at nanoscale

Researchers from the Institute of Organic Chemistry and Biochemistry of the CAS (IOCB Prague), Institute of Physics of the CAS (IP CAS) and Palacký University...

Im Focus: Hybrid optics bring color imaging using ultrathin metalenses into focus

For photographers and scientists, lenses are lifesavers. They reflect and refract light, making possible the imaging systems that drive discovery through the microscope and preserve history through cameras.

But today's glass-based lenses are bulky and resist miniaturization. Next-generation technologies, such as ultrathin cameras or tiny microscopes, require...

Im Focus: Stem cell divisions in the adult brain seen for the first time

Scientists from the University of Zurich have succeeded for the first time in tracking individual stem cells and their neuronal progeny over months within the intact adult brain. This study sheds light on how new neurons are produced throughout life.

The generation of new nerve cells was once thought to taper off at the end of embryonic development. However, recent research has shown that the adult brain...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

2nd International Conference on High Temperature Shape Memory Alloys (HTSMAs)

15.02.2018 | Event News

Aachen DC Grid Summit 2018

13.02.2018 | Event News

How Global Climate Policy Can Learn from the Energy Transition

12.02.2018 | Event News

 
Latest News

Stiffness matters

22.02.2018 | Life Sciences

Magnetic field traces gas and dust swirling around supermassive black hole

22.02.2018 | Physics and Astronomy

First evidence of surprising ocean warming around Galápagos corals

22.02.2018 | Earth Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>