Skyrmions – which are swirling nanosized magnetic textures – have been shown to exist in layered systems, with a heavy metal placed beneath a ferromagnetic material.
Due to the interaction between the different materials, an interfacial symmetry breaking interaction, known as the Dzyaloshinskii-Moriya interaction (DMI), is formed, and this helps to stabilise a skyrmion.
However, without an out-of-plane magnetic field present, the stability of the skyrmion is compromised.
To address these limitations, the researchers worked towards creating stable magnetic skyrmions at room temperature without the need for a biasing magnetic field.
The NUS team found that a large DMI could be maintained in multilayer films composed of cobalt and palladium, and this is large enough to stabilise skyrmion spin textures.
“It has long been assumed that there is no DMI in a symmetric structure like the one present in our work, hence, there will be no skyrmion,” Dr Shawn Pollard explained.
“It is unexpected for us to find both large DMI and skyrmions in the multilayer film we engineered. What’s more, these nanoscale skyrmions persisted even after the removal of an external biasing magnetic field, which are the first of their kind.”
“Without the need for a biasing field, the design and implementation of skyrmion based devices are simplified,” associate professor Yang Hyunsoo added.
“The small size of the skyrmions, combined with the incredible stability generated here, could be potentially useful for the design of next-generation spintronic devices that are energy efficient and can outperform current memory technologies.”