Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Simple detection of magnetic skyrmions

06.10.2015

New physical effect: researchers discover a change of electrical resistance in magnetic whirls

At present, tiny magnetic whirls – so called skyrmions – are discussed as promising candidates for bits in future robust and compact data storage devices. At the University of Hamburg these exotic magnetic structures were recently found to exist in ultrathin magnetic layers and multilayers, similar to the ones used in current hard-disk drives and magnetic sensors.


Figure: Magnetic whirls with a diameter of only a few nanometers occur in a thin film of palladium and iron (bottom, cones represent single atoms of the surface and they point into the direction of the atomic magnets). The resistance, measured with a metallic probe close to the surface changes inside the skyrmion as compared to its surrounding (top, experimental data across a skyrmion, see original publication). The change in resistance is continuous and becomes strongest, when the canting between neighboring atomic magnets is largest, in this case in the skyrmion center.

(Image: C. Hanneken, University of Hamburg)

However, up to now an additional magnet was necessary for a read-out of skyrmions. Now researchers from the University of Hamburg and the Christian-Albrechts-Universität in Kiel have demonstrated that skyrmions can be detected much more easily because of a drastic change of the electrical resistance in these magnetic whirls. For future data storage concepts this promises a significant simplification in terms of fabrication and operation.

Stable whirls in magnetic materials (see figure) were predicted over 25 years ago, but the experimental realization was achieved only recently. The discovery of such skyrmions in thin magnetic films and multilayers, already used in today’s technology, and the possibility to move these skyrmions at very low electrical current densities, has opened the perspective to use them as bits in novel data storage devices.

Up to now individual magnetic whirls were detected either by electron microscopy or by the resistance change in a tunnel contact with a magnetic probe. Employing a scanning tunneling microscope researchers of the University of Hamburg were now able to demonstrate that the resistance changes also when a non-magnetic metal is used in such a measurement.

‘In our experiment we can move a metallic tip over a surface with atomic-scale precision, and in this way we can measure the resistance at different positions in a skyrmion’ says Christian Hanneken, a PhD student in the group of Prof. Roland Wiesendanger. This enables the proof for the locally varying resistance within the magnetic whirl. ‘We found a resistance change of up to 100%, allowing a simple detection scheme for skyrmions’, as Dr. Kirsten von Bergmann explains.

In collaboration with theoretical physicists from the University of Kiel the researchers were able to identify the origin of the resistance change in the magnetic whirl: it is due to the canting between the atomic magnets from one atom to the next (see figure). The larger the angle between the adjacent atomic magnets, the stronger is the change in electrical resistance.

‘Electrons have a spin, and thus they interact with magnetic structures’, says Prof. Stefan Heinze from the University of Kiel. When the electrons are travelling through a magnetic whirl, they feel the canting between the atomic magnets, leading to a local resistance change of the material. ‘We were able to understand this effect by performing extensive numerical computer simulations of the electronic properties and developed a simple model for this effect’, as the PhD student Fabian Otte explains.

In future applications this newly discovered effect could be exploited to read out skyrmionic bits in a simple fashion. The possibility to use arbitrary metallic electrodes significantly simplifies the fabrication and operation of such novel storage devices.


Original publication:
Electrical detection of magnetic skyrmions by tunnelling non-collinear magnetoresistance,
Christian Hanneken, Fabian Otte, André Kubetzka, Bertrand Dupé, Niklas Romming, Kirsten von Bergmann, Roland Wiesendanger and Stefan Heinze, Nature Nanotechnology, Online publication: 05.10.2015,
DOI: 10.1038/nnano.2015.218.

Additional information:
Dr. Kirsten von Bergmann
Universität Hamburg
Jungiusstr. 9A/11A
D-20355 Hamburg
Germany
e-mail: kbergman@physnet.uni-hamburg.de
Phone: +49- 40 - 4 28 38 - 62 95

Weitere Informationen:

http://www.nanoscience.de
http://www.sfb668.de

Heiko Fuchs | idw - Informationsdienst Wissenschaft

More articles from Information Technology:

nachricht Drones that drive
27.06.2017 | Massachusetts Institute of Technology, CSAIL

nachricht Ahead of the Curve
27.06.2017 | Institute of Science and Technology Austria

All articles from Information Technology >>>

The most recent press releases about innovation >>>

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

Im Focus: Can we see monkeys from space? Emerging technologies to map biodiversity

An international team of scientists has proposed a new multi-disciplinary approach in which an array of new technologies will allow us to map biodiversity and the risks that wildlife is facing at the scale of whole landscapes. The findings are published in Nature Ecology and Evolution. This international research is led by the Kunming Institute of Zoology from China, University of East Anglia, University of Leicester and the Leibniz Institute for Zoo and Wildlife Research.

Using a combination of satellite and ground data, the team proposes that it is now possible to map biodiversity with an accuracy that has not been previously...

Im Focus: Climate satellite: Tracking methane with robust laser technology

Heatwaves in the Arctic, longer periods of vegetation in Europe, severe floods in West Africa – starting in 2021, scientists want to explore the emissions of the greenhouse gas methane with the German-French satellite MERLIN. This is made possible by a new robust laser system of the Fraunhofer Institute for Laser Technology ILT in Aachen, which achieves unprecedented measurement accuracy.

Methane is primarily the result of the decomposition of organic matter. The gas has a 25 times greater warming potential than carbon dioxide, but is not as...

Im Focus: How protons move through a fuel cell

Hydrogen is regarded as the energy source of the future: It is produced with solar power and can be used to generate heat and electricity in fuel cells. Empa researchers have now succeeded in decoding the movement of hydrogen ions in crystals – a key step towards more efficient energy conversion in the hydrogen industry of tomorrow.

As charge carriers, electrons and ions play the leading role in electrochemical energy storage devices and converters such as batteries and fuel cells. Proton...

Im Focus: A unique data centre for cosmological simulations

Scientists from the Excellence Cluster Universe at the Ludwig-Maximilians-Universität Munich have establised "Cosmowebportal", a unique data centre for cosmological simulations located at the Leibniz Supercomputing Centre (LRZ) of the Bavarian Academy of Sciences. The complete results of a series of large hydrodynamical cosmological simulations are available, with data volumes typically exceeding several hundred terabytes. Scientists worldwide can interactively explore these complex simulations via a web interface and directly access the results.

With current telescopes, scientists can observe our Universe’s galaxies and galaxy clusters and their distribution along an invisible cosmic web. From the...

Im Focus: Scientists develop molecular thermometer for contactless measurement using infrared light

Temperature measurements possible even on the smallest scale / Molecular ruby for use in material sciences, biology, and medicine

Chemists at Johannes Gutenberg University Mainz (JGU) in cooperation with researchers of the German Federal Institute for Materials Research and Testing (BAM)...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Plants are networkers

19.06.2017 | Event News

Digital Survival Training for Executives

13.06.2017 | Event News

Global Learning Council Summit 2017

13.06.2017 | Event News

 
Latest News

Touch Displays WAY-AX and WAY-DX by WayCon

27.06.2017 | Power and Electrical Engineering

Drones that drive

27.06.2017 | Information Technology

Ultra-compact phase modulators based on graphene plasmons

27.06.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>