Temperature evolution of skyrmion stability and formation mechanism in chiral multilayers

Magnetic skyrmions – nanoscale topological spin structures stabilised by chiral interactions – are promising candidates for next-generation computing. As such devices may operate at room temperature and beyond, it is critical to study the role of temperature on skyrmions. Skyrmions can form from magnetic stripes with increasing field via two distinct mechanisms – the reversible shrinking of a stripe into a skyrmion or the irreversible fission of a stripe into multiple skyrmions [1]. In this work, we investigate Ir/Fe/Co/Pt multilayers [2] over temperatures of 100 - 350K using first order reversal curve (FORC) magnetometry [3] and Lorentz transmission electron microscopy (LTEM). We demonstrate an increased tendency for fission, resulting in increased skyrmion densities with increasing temperatures. With theoretical modelling, we interpret our results as the consequence of the temperature dependence of the fission energy barrier. These findings establish temperature as an important tuning parameter for skyrmion formation and stability, which is crucial to the realisation of skyrmionic devices.

[1] Tan et al., Physical Review Materials (2020), In Press.
[2] Soumyanarayanan, A. et al., Nature Materials 16, 898-904 (2017).
[3] J. E. Davies et al., Physical Review B 70, 224434 (2004).