Characterization of magnetic nanovortices simplified

December 20, 2016
Illustration of a Skyrmion. Credit: Nature Communications

Magnetic nanovortices, so-called "skyrmions", count among the most promising candidates for the future of information technology. Processors and storage media making use of these tiny structures could one day lead to the further miniaturization of IT devices and improve their energy efficiency significantly. Materials possessing suitable vortices can be identified in particular by their topological charge, an essential characteristic of skyrmions. To determine this property experimentally has up to now been a very laborious process. Physicists from Jülich have now put forward a simpler method which could speed up the screening of suitable materials, using X-rays.

The magnetic moment of an atom has two contributions, the spin part, which arises from the alignment of the intrinsic of the electrons, and the orbital part,related to the coordinated of the electrons. The former is the dominant source of the of the atoms in a solid, while the latter is usually found when spin-orbit coupling is active. However, a few years ago it was found that – even without – an orbital moment can be finite. To make that happen, at least three magnetic atoms have to be combined, forming a trimer with a non-collinear and non-planar magnetic structure.

A team of theoretical physicists from the Jülich Institute "Quantum Theory of Materials" (PGI-1/IAS-1) has now analysed the effect in detail for such magnetic trimers, and examined the consequences for skyrmions. The scientists propose a protocol on how to probe this contribution to the orbital magnetism, and furthermore, how to employ it to detect and distinguish different types of skyrmions. "One of the most important quantities characterizing the skyrmion is the topological charge, also known as the 'skyrmion number'", explains Dr. Manuel dos Santos Dias, Postdoc in institute's Young Investigators Group "Functional Nanoscale Structure Probe and Simulation Laboratory"(Funsilab). "A direct measurement of the topological charge has been difficult, as it requires a detailed map of the three-dimensional magnetic structure or finding certain signatures in transport experiments. Therefore, only very few experiments have been undertaken. Skyrmions with a richer internal structure have also attracted attention recently, and our proposed protocol naturally enables its experimental determination."

Jun.-Prof. Samir Lounis, head of Funsilab, adds: "We propose a spectroscopic approach using X-ray magnetic circular dichroism to measure this quantity fast and efficiently. The technique could be implemented at any synchrotron covering the soft X-ray regime."

Explore further: Team ahead of the 'curve' in magnetic study

More information: Manuel dos Santos Dias et al. Chirality-driven orbital magnetic moments as a new probe for topological magnetic structures, Nature Communications (2016). DOI: 10.1038/ncomms13613

Related Stories

Team ahead of the 'curve' in magnetic study

September 21, 2016

When a baseball pitcher uncorks a nasty curveball, the spinning motion of the ball forces air to flow around it at different speeds, causing the ball to "break" in one direction.

Frustrated magnets point towards new memory

September 23, 2015

Theoretical physicists from the University of Groningen, supported by the FOM Foundation, have discovered that so-called 'frustrated magnets' can produce skyrmions, tiny magnetic vortices that may be used in memory storage. ...

Skyrmions—magnetic vortices for IT of the future

June 3, 2016

Magnetic vortices - so-called skyrmions - were predicted theoretically more than 25 years ago, but it has only been possible to observe them experimentally in magnetic materials in recent years. Skyrmions are stable, can ...

Magnetic vortices with electric sense

August 17, 2012

In the field of magnetic materials, a rapidly expanding area of study concerns stable nanometer-scale spin arrangements. Spins are the fundamental magnetic entities in solids, and patterns made of several spins could be useful ...

Recommended for you

Graphene photodetector enhanced by fractal golden 'snowflake'

January 16, 2017

(Phys.org)—Researchers have found that a snowflake-like fractal design, in which the same pattern repeats at smaller and smaller scales, can increase graphene's inherently low optical absorption. The results lead to graphene ...

Nanoscale view of energy storage

January 16, 2017

In a lab 18 feet below the Engineering Quad of Stanford University, researchers in the Dionne lab camped out with one of the most advanced microscopes in the world to capture an unimaginably small reaction.

Scientists create first 2-D electride

January 11, 2017

(Phys.org)—Researchers have brought electrides into the nanoregime by synthesizing the first 2D electride material. Electrides are ionic compounds, which are made of negative and positive ions. But in electrides, the negative ...

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.