Nature Commun. 6, 7638 (2015)

Skyrmions are nanoscale spin textures distinguished by their topological stability. They have been observed in several chiral magnets, both in bulk and thin-film form, where they are stable in well-defined pockets of the magnetic field-temperature phase diagram. Besides a fundamental interest generated by their emerging electromagnetic properties, they are attracting significant attention as promising candidates for information carriers in low-power, dense memory devices. A major hurdle towards mainstream applications is the fact that skyrmions have only been observed at a maximum temperature of 278 K. Now, Yoshinori Tokura and colleagues have shown that skyrmion crystals can form at room temperature and above in Co–Zn–Mn metallic alloys, which are cubic chiral magnets with a different chiral space group compared with the compounds previously investigated.

The researchers — who are based at the RIKEN Center for Emergent Matter Science, University of Tokyo, Paul Scherrer Institute and EPFL — investigated the presence of a skyrmion phase in a series of these alloys with varying composition using multiple experimental techniques, including Lorentz transmission electron microscopy, magnetization measurements and small-angle neutron scattering. Skyrmions were found in samples with a thickness of 150 nm at temperatures from 283 to 345 K, under application of a magnetic field of a few hundred oersteds. In bulk form, skyrmions form in a narrower temperature range, from 311 to 320 K, and for applied magnetic fields of around 1 kOe.