Two independent magnetic skyrmion phases discovered in a single material

Two independent magnetic skyrmion phases discovered in a single material
The new magnetic phase was discovered and studied at the instrument SANS-1 of the research neutron source Heinz Maier-Leibnitz © Wenzel Schürmann - TUM

For the first time, a team of researchers have discovered two different magnetic skyrmion phases in a single material, leading to a better understanding of magnetic structures.

Researchers from Technical Universities of Munich and Dresden and the University of Cologne, Germany, have discovered the two magnetic skyrmion phases and can now better study the properties of the structures.

Similar structures to that of a whirlpool can be observed in magnetic materials. Magnetic whirls are formed when the magnetic moments are aligned in a circular fashion. These so-called skyrmions are not just interesting for basic research – because of their stability and their tiny dimensions – but they could be key for the development of future magnetic storage.

For this reason, they are at the centre of current research, with one of the key questions being: when and how do they occur?

Now, a team of researchers has shown for the first time that magnetic skyrmions can form due to different mechanisms in separate phases in the same material. Their discovery in the chiral magnet Cu2OSeO3 near absolute zero temperature (-273.15°C) is published in the scientific journal Nature Physics.

Can these magnetic structures be used for magnetic storage?

Physicist Christian Pfleiderer of TUM, who led this research study, said: “Skyrmions usually exist in a single thermodynamic parameter range, that is, a certain range of temperature and magnetic or electric field strength. Indeed, this is the case for all the materials in which skyrmions have been found so far.

“This imposes a constraint for the creation and technical use of skyrmions, since they are only stable as long as one finds and abides to the exact physical parameters required. Now, in a single material we have found two different skyrmion phases, with two different sets of parameters. Previously, it was thought that the new mechanism is very weak. But now it turns out that there are many more possibilities to create and control skyrmions than we have thought.”

Magnetic skyrmion phases at low temperatures

Alfonso Chacon discovered the new phase, when he studied the metastable properties of an already known skyrmion phase at the research neutron source of TUM, he said: “These metastable properties interests us, because this way we can learn about the related energies and the stability of skyrmions. This helps us to understand the mechanism of their formation and how they are destroyed. While we performed these measurements I discovered that something very unexpected and odd was going on.”

Dr Markus Garst, from the Institute of Theoretical Physics at the Technical University of Dresden, concluded: “At low temperatures quantum effects play an increasingly larger role.

“These influence also the physical properties of the magnetic skyrmions. The new findings allow to study quantum skyrmions in magnets in detail.”

According to the Technical University of Dresden, the discovery and study of the two different magnetic skyrmion phases took place at the small angle neutron scattering experiment SANS-1 at the Maier Leibnitz Zentrum at the Research Neutron Source Heinz Maier-Leibnitz (FRM II) of TUM.

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